Saturated Zone Site-Scale Flow Model Rev 02, ICN 00
 
MDL-NBS-HS-000011

November 2004
 
1. PURPOSE 
The purpose of this model report is to document the components of the saturated zone (SZ) 
site-scale flow model at Yucca Mountain, Nevada, in accordance with AP-SIII.10Q, Models. 
This report provides validation and confidence in the flow model that was developed for site 
recommendation and will be used to provide flow fields in support of the total system 
performance assessment (TSPA) for the license application (LA). The output from this report 
provides the flow model used in the site-scale SZ transport model, which provides output to the 
SZ flow and transport model abstraction. In particular, the output from the SZ site-scale flow 
model, containing the flow fields, flow paths and specific discharge, is used by the SZ site-scale 
transport model to simulate the groundwater flow pathways and radionuclide transport to the 
accessible environment for use in the TSPA calculations. Figure 1-1 shows the relationship of 
this report to other SZ reports that also pertain to the SZ flow and transport. The figure also 
depicts the relationship between SZ models and analyses. It should be noted that Figure 1-1 does 
not contain a complete representation of the data and parameter inputs and outputs of all SZ 
reports, nor does it show inputs external to this suite of SZ reports. 
Since the development, calibration, and validation of the SZ site-scale flow model, Calibration 
of the Site-Scale Saturated Zone Flow Model (BSC 2001 [DIRS 155974]), more data have been 
gathered and analyses have been completed. The data include new stratigraphic and waterlevel 
data from Nye County wells, single- and multiple-well hydraulic testing data, and new 
hydrochemistry data. New analyses include the 2001 Death Valley Regional Flow System 
(DVRFS) model (D'Agnese et. al 2002 [DIRS 158876]), the creation of an alternative 
Hydrogeologic Framework Model (HFM), (BSC 2004 [DIRS 170008]), and a revised 
unsaturated zone (UZ) flow model (BSC 2004 [DIRS 169861]). The new data and analyses were 
used to construct alternative SZ flow models that are presented in this report to evaluate the 
impact of the new data and analyses on the predictions of the SZ site-scale flow model. 
The intended use of this work is to provide a flow model that generates flow fields that are used 
to simulate radionuclide transport in saturated porous rock and alluvium under natural or forced 
gradient flow conditions. The SZ site-scale flow model simulations were completed using the 
three-dimensional, finite-element heat and mass transfer computer code, FEHM V2.20, 
STN: 10086-2.20-00 (LANL 2003 [DIRS 161725]). Concurrently, the process-level transport 
model and methodology for calculating radionuclide transport in the SZ at Yucca Mountain 
using FEHM are described in Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036]). 
The velocity fields are calculated by the flow model, described herein, independent of the 
transport processes, and are then used as inputs to the transport model. Justification for this 
abstraction is presented in Saturated Zone Flow and Transport Model Abstraction (BSC 2004 
[DIRS 170042]). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 1-2 November 2004 
NOTE: This figure is a simplified representation of the flow of information among SZ reports. See the Document 
Input Reference System (DIRS) of each report for a complete listing of data and parameter inputs. This 
figure does not show inputs external to this suite of SZ reports. 
FEPs = features, events, and processes; SZ = saturated zone; TSPA = total system performance assessment. 
Figure 1-1. Generalized Flow of Information Among Reports Pertaining to Flow and Transport in the SZ 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 1-3 November 2004 
This model report is governed by the Office of Civilian Radioactive Waste Management 
Technical Work Plan for: Natural System - Saturated Zone Analysis and Model Report 
Integration (BSC 2004 [DIRS 171421], Work Package ARTM01). All activities listed in the 
technical work plan (TWP) that are appropriate to the SZ site-scale flow model are documented 
in this report. 
Model-validation activities presented in this report lead to increased confidence that the model is 
a reasonable representation of groundwater flow likely to occur at Yucca Mountain near the 
repository site. Model-validation activities consist of comparison between observed data and 
model predictions. Comparisons are presented between: 
 Predicted and observed hydraulic heads 
 Hydraulic properties obtained from model calibrations and those obtained from 
hydraulic field and laboratory testing 
 Groundwater temperature data predicted by the model and those measured in wells 
 Flow path lines obtained from the model and those inferred from analysis of field 
hydrochemistry and isotopic data. 
Alternative conceptual models and the implications of these models for flow field, flow paths, 
and transport times predictions are evaluated relative to the SZ site-scale flow model. 
A number of relevant features, events, and processes (FEPs) are addressed in this report 
(Section 6.2). 
Uncertainty inherent in the input parameters is discussed in Section 4 and, as appropriate, 
propagated in Section 8. Uncertainty inherent to conceptualization and modeling is discussed in 
Section 6 and propagated, as appropriate, in Section 8. 
The SZ site-scale flow model is limited to steady state use for TSPA purposes. When using the 
SZ site-scale flow model for TSPA calculations, there are limitations that must be noted in 
regard to the following: changes to input parameter values, useable path-line distances, and 
overall model recharge fluxes. These are discussed more fully in Section 8. 
Important technical issues addressed by this model report, and the sections in which they are 
discussed, include: 
 Horizontal and vertical anisotropy, reasonable range for uncertainty (Sections 6.4.3 
and 6.8.3.2) 
 Updated potentiometric data (Section 6.4.4) 
 Alternative conceptual flow model for Solitario Canyon fault (Section 6.7.2) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 1-4 November 2004 
 Validation of SZ site-scale flow model (Section 7) 
 Comparison of fluxes with those of the Death Valley regional flow model 
(Section 6.6.2.2) 
Modeling objectives addressed in this model report include: 
 Reflect the current understanding of the SZ flow 
 Enhance model validation and uncertainty analyses 
 Incorporate new data collected since the TSPA-SR (CRWMS M&O 2000 
[DIRS 153246]). 
This report is cited by Features, Events, and Processes in SZ Flow and Transport, (BSC 2004 
[DIRS 170013]) and Engineered Barrier System Features, Events, and Processes, (BSC 2004 
[DIRS 170900]) . 
One variation from the technical work plan (TWP) (BSC 2004 [DIRS 171421]) was required to 
complete this work. The change from the TWP concerned the inclusion of the FEP 22.03.02.0A, 
Rock properties of Host Rock and other Units. This was made to be consistent with results of 
SZ FEP identification and screening process as documented in the SZ FEPs report. This is an 
implicit rather than explicit inclusion carried forward from the upstream reports. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 2-1 November 2004 
2. QUALITY ASSURANCE 
Development of this model report and the supporting modeling activities are subject to the Office 
of Civilian Radioactive Waste Management quality assurance program as indicated in the TWP 
(BSC 2004 [DIRS 171421], Work Package ARTM01). Approved quality assurance procedures 
identified in Section 4 of the TWP have been used to conduct and document the activities 
described in this model report. Section 8 of the TWP also identifies the methods used to control 
the electronic management of data. 
This model report provides calibrated values for hydrologic properties of the SZ portion of the 
lower natural barrier (i.e., UZ below the repository horizon and SZ below and downgradient 
from the repository), which is important to the demonstration of compliance with the postclosure 
performance objectives prescribed in 10 CFR 63.113 [DIRS 156605]. Therefore, the lower 
natural barrier is classified on the Q-List (BSC 2004 [DIRS 168361], Table A-2) as SC (Safety 
Category), reflecting its importance to waste isolation, as defined in AP-2.22Q, Classification 
Analyses and Maintenance of the Q-List. This report contributes to the analysis and modeling 
data used to support performance assessment; the conclusions do not directly impact engineered 
features important to safety, as defined in AP-2.22Q. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 2-2 November 2004 
INTENTIONALLY LEFT BLANK 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 3-1 November 2004 
3. USE OF SOFTWARE 
3.1 SOFTWARE TRACKED BY CONFIGURATION MANAGEMENT 
The computer codes used directly in the SZ site-scale flow model are summarized in Table 3-1. 
The qualification status of the software is indicated in the Software Configuration 
Management (SCM) database. All software was obtained from SCM and is appropriate for the 
application. Qualified codes were used only within the range of validation as required by 
LP-SI.11Q-BSC, Software Management. 
All computer codes listed in Table 3-1 were selected for use in the analysis report because they 
satisfy at least one of the following conditions: 
 Were developed specifically for the tasks considered in this report (these codes are 
denoted with * in the Table 3-1 footnote) 
 Were developed for the Yucca Mountain Project (YMP) (these codes are denoted with 
** in the Table 3-1 footnote) 
 Were best available codes for modeling conditions specific to the YMP. 
The codes developed specifically for the tasks considered in this report and for the YMP were 
validated for the parameter ranges expected for Yucca Mountain. The range of use and the 
limitations on output of each code are specified in the Software Management Report (SMR) of 
each code. As it can be concluded from these SMRs, the limitations on input and output should 
only be considered when these codes are used outside of YMP. Otherwise, no special limitations 
on input and output exist. The codes that fall into the best category are described in 
Sections 3.1.1 through 3.1.6. 
Table 3-1. Computer Codes Used in the SZ Site-Scale Flow Model 
Software Name and 
Version (V) 
Software 
Tracking 
Number 
(STN) Description 
Computer Type, Platform, 
and Location 
Date 
Baselined 
FEHM 
V2.20 LANL (2003 
[DIRS 161725]) 
10086-2.20-00 Flow modeling / flow and 
transport modeling 
(particle tracking) 
Sun Ultra Sparc with Sun 
Solaris 5.7 or 5.8 operating 
system at LANL 
1/28/03 
LaGriT 
V1.0 LANL (2001 
[DIRS 149148]) 
10212-1.0-00 Software package for 
grid generation, analysis, 
and visualization. 
Sun Ultra Sparc with Sun 
OS 2.7 operating system at 
LANL 
8/8/01 
NETPATH 
V2.13 LANL (2001 
[DIRS 149910]) 
10303-2.13-00 Groundwater age 
correction for figures in 
document 
PC with Windows DOS 
operating system at LANL 
8/8/01 
PEST 
V5.5 Watermark 
Computing (2002 
[DIRS 161564]) 
10289-5.5-00 Preconditioning and 
parameter optimization 
for FEHM (LANL 2003 
[DIRS 161725]) runs 
Sun Ultra Sparc with Sun 
Solaris 5.7 or 5.8 operating 
system at LANL 
12/3/02 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 3-2 November 2004 
Table 3-1. Computer Codes Used in the SZ Site-Scale Flow Model (Continued) 
Software Name and 
Version (V) 
Software 
Tracking 
Number 
(STN) Description 
Computer Type, Platform, 
and Location 
Date 
Baselined 
* prepare_ 
features_for_ 
surfer V1.0 
[DIRS 171911] 
11091-1.0-00 Postprocessor to write 
visualization for Surfer 
Sun Ultra Sparc with Sun 
OS 2.7 or 2.8 operating 
system at LANL 
6/23/03 
STRAT2AVS 
V1.0 LANL (2003 
[DIRS 163069]) 
11028-1.0-00 Preprocessor used to 
extract hydrogeologic 
surface data from the 
USGS HFM. 
SGI with Irix64 operating 
system at LANL 
3/3/03 
*READPATHS V1.0 
LANL (2000 
[DIRS 150459]) 
11089-1.0-00 Postprocessor for FEHM 
(LANL 2003 
[DIRS 161725]) to view 
flow lines 
Sun Ultra Sparc with Sun 
OS 2.7 or 2.8 operating 
system at LANL 
6/23/03 
* write_temps 
V1.0 
[DIRS 171891] 
11090-1.0-00 Preprocessor for FEHM 
(LANL 2003 
[DIRS 161725]) to adjust 
viscosity values 
Sun Ultra Sparc with Sun 
Solaris 5.7 or 5.8 operating 
system at LANL 
6/27/03 
**Extract 
V1.0 SNL (2002 
[DIRS 163070]) 
10955-1.0-00 Pre/postprocessor used 
to extract lateral flow 
data from the USGS 
regional flow model 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
**Extract 
V1.1 SNL (2002 
[DIRS 163071]) 
10955-1.1-00 Pre/postprocessor used 
to extract lateral flow 
data from the USGS 
2001 regional flow model 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
**EXT_RECH 
V1.0 SNL (2002 
[DIRS 163072]) 
10958-1.0-00 Pre/postprocessor used 
to extract recharge data 
from the USGS regional 
flow model 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
**Mult_Rech 
V1.0 SNL (2002 
[DIRS 163073]) 
10959-1.0-00 Pre/postprocessor that 
scales recharge data 
from the USGS regional 
flow model and maps the 
data to a new grid 
Sun UltraSPARC - SunOS 
5.7, Solaris 2.7 operating 
system at SNL 
12/18/02 
**WTCONVYD 
V1.00 SNL (2002 
[DIRS 163835]) 
10815-1.00-00 Used to calculate the 
estimated elevation of 
the water table for wetter 
climatic conditions 
PC with Windows 98 at SNL 7/15/02 
**Xread_Distr_Rech 
V1.0 SNL (2002 
[DIRS 163074]) 
10960-1.0-00 Pre/postprocessor used 
to extract recharge data 
from the USGS 1999 
regional flow model 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
**Xread_Distr_Rech_- 
UZ V1.0 SNL (2002 
[DIRS 163075]) 
10961-1.0-00 Pre/postprocessor that 
maps recharge data onto 
a new grid excluding the 
UZ flow model region 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
**Xread_ 
Reaches 
V1.0 SNL (2002 
[DIRS 163076]) 
10962-1.0-00 Pre/postprocessor that 
maps local recharge from 
four stream channels 
onto a new grid 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 3-3 November 2004 
Table 3-1. Computer Codes Used in the SZ Site-Scale Flow Model (Continued) 
Software Name and 
Version (V) 
Software 
Tracking 
Number 
(STN) Description 
Computer Type, Platform, 
and Location 
Date 
Baselined 
**Xwrite_Flow_ 
New 
V1.0-125 SNL (2002 
[DIRS 163077]) 
10963-1.0-125- 
00 
Used both to map the 
combined UZ and SZ 
site-scale fluxes onto a 
125-m grid and to create 
a flux file that is 
compatible with FEHM 
LANL 2003 
[DIRS 161725]) flow 
macros 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
**Zone 
V1.0 SNL (2002 
[DIRS 163078]) 
10957-1.0-00 Used to extract zonal 
designation data from the 
USGS 2001 regional flow 
model. 
Sun UltraSPARC - SunOS 
5.7 operating system at 
SNL 
12/11/02 
NOTE: * These codes were developed specifically for the tasks considered in this report 
** These codes were developed for the YMP 
DOS=disk operating system; HFM = hydrogeologic framework model; LANL=Los Alamos National Laboratory; 
PC=personal computer; SNL=Sandia National Laboratories; SZ=saturated zone; USGS=U.S. Geological Survey; 
UZ=unsaturated zone. 
3.1.1 Parameter Optimization 
In this report, the parameter estimation code PEST V5.5, STN: 10289-5.5-00 (Watermark 
Computing 2002 [DIRS 161564]) is used to perform the parameter optimization for the 
hydrogeologic and feature permeabilities. The PEST code is based on the Levenberg-Marquardt 
(LM) algorithm. This software was not used to generate any model output. It is used to calibrate 
the flow model by minimizing the difference between observed and predicted head and boundary 
fluxes values. 
3.1.2 Flow Modeling 
The FEHM code V2.20, STN: 10086-2.20-00 (LANL 2003 [DIRS 161725]) is used to solve for 
a steady-state flow solution and to provide model output. The range of validation for the FEHM 
code was developed with the YMP specific data. Consequently, the input and output parameters 
are within their validation ranges. 
3.1.3 Particle Tracking 
The FEHM code is used within its validated range to determine the streamlines (particle tracks) 
with the steady-state flow solution (see Section 3.1.2). FEHM has two different particle-tracking 
routines. This study uses the sptr macro for particle tracking. The particle-tracking portion of 
FEHM has been verified in Site-Scale Saturated Zone Transport (BSC 2004 [DIRS 170036], 
Section 6.4.2). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 3-4 November 2004 
3.1.4 Grid Generation 
The Los Alamos grid generation software package LaGriT, V1.0, STN: 10212-1.0-00 
(LANL 2001 [DIRS 149148]) is used within its validation limits for creation, analysis, and 
visualization of grids. LaGriT is a set of software macros that uses the HFM conceptual model 
data to create computational grids. The software macros translate the coordinate and attribute 
information into a form that is valid for finite-element heat and mass compilations (FEHM). 
3.1.5 Framework Translation 
The software STRAT2AVS V1.0, STN: 11028-1.0-00 (LANL 2003 [DIRS 163069]) is used 
within its validated range to read stratamodel geocellular modeling files representing a 
three-dimensional hydrogeologic framework and then write ASCII surface files with x,y,z 
coordinate locations and quadrilateral element connectivity. These binary stratamodel 
geocellular modeling files are both written and read by STRATAMODEL and represent the 
HFM. This HFM provides the geologically defined internal geometry for flow and transport 
process models and can be converted into a mesh for use in groundwater flow and transport 
modeling codes. 
3.1.6 Corrections of 14C Ages in Field Data 
NETPATH V2.13, STN: 10303-2.13-00 (LANL 2001 [DIRS 149910]) is a public-domain 
geochemical software, which was used within its validation range in this report to correct 14C 
ages for the effects of chemical reactions. The results of all calculations using NETPATH were 
checked with order-of-magnitude estimations. 
3.2 EXEMPT SOFTWARE 
Commercial, off-the-shelf software used in support of this modeling analysis to create data plots 
is exempt from the qualification requirements of LP-SI.11Q-BSC, Software Management but 
meets the acceptance criteria of being able to correctly produce plots of acceptable graphic 
quality in formats suitable for incorporation into this model report. 
 EXCEL 98-SR-1 was used to preprocess data from the U.S. Geological Survey (USGS) 
traces for FEHM zone definitions. The calculation of basic statistics was used with 
standard functions only. 
 SURFER for Windows, V7.0 was used for plotting and visualization of analysis results 
in figures shown in this report. The results were visually checked for correctness. 
 TECPLOT, V8.0 was used for plotting and visualization of analysis results in figures 
shown in this report. The results were visually checked for correctness. 
 FORTNER PLOT SUN Workstations V1.3 was used for visualizations in this analysis 
and documentation for plotting graphs. 
 GMV and Adobe Illustrator V10 were used to visualize and illustrate the computational 
mesh and related data. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 3-5 November 2004 
 AquaChem, V3.7, was used to create trilinear diagrams showing proportions of major 
ions in groundwater and x-y scatter plots. 
 Adobe Illustrator was used to create flow-path maps. 
The output from SURFER, TECPLOT, Excel, Adobe Illustrator, and AquaChem were visually 
checked for correctness. This output can be found in the Technical Data Management System 
within data packages that have been assigned data tracking number (DTN) numbers. The DTNs 
are identified in appropriate places throughout Section 6 of this model report to allow the 
independent reviewer to reproduce or verify results by visual inspection or hand calculation. 
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MDL-NBS-HS-000011 REV 02 3-6 November 2004 
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Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 4-1 November 2004 
4. INPUTS 
4.1 DIRECT INPUT 
Input information used in this model report comes from several sources, which, along with their 
DTNs, are summarized in Table 4-1. The data referenced in Table 4-1 contain information 
necessary to construct the numerical model, set boundary conditions, calibrate the model, and 
check the calibration. The data are fully appropriate for the SZ site-scale flow model. All data 
listed in Table 4-1 are qualified. 
Table 4-1. Direct Input Data Sources 
Data Description Data Tracking Number File Name 
Water level and head distributions GS000508312332.001 [DIRS 149947] All 
Borehole data from water-level data analysis GS010908312332.002 [DIRS 163555] All 
HFM for SZ site-scale flow and transport 
model, containing unit surfaces 
GS030208312332.001 [DIRS 163087] All 
Distribution of recharge flux SN9908T0581999.001 [DIRS 132867] Boundaries.xls, 
Combined.xls 
Feature and fault distributions GS010908314221.001 [DIRS 162874] All 
Plots of temperature profiles in wells MO0102DQRBTEMP.001 [DIRS 154733] All 
HFM=hydrogeologic framework model; SZ=saturated zone. 
The data listed in Table 4-1 are direct model inputs, after appropriate manipulation by the 
software listed in Table 3-1. The indirect input includes the lateral fluxes that are stored in the 
same DTN as the distribution of recharge fluxes in Table 4-1. 
4.2 CRITERIA 
The general requirements to be satisfied by the TSPA are stated in 10 CFR 63.114 
[DIRS 156605]. Technical requirements to be satisfied by the TSPA are identified in the Project 
Requirements Document (Canori and Leitner 2003 [DIRS 166275]). The acceptance criteria that 
will be used by the U.S. Nuclear Regulatory Commission to determine whether the technical 
requirements have been met are identified in the Yucca Mountain Review Plan, Final Report 
(YMRP) (NRC 2003 [DIRS 163274]). The requirements and criteria, which had been identified 
for this report, are summarized in Table 4-2. 
Table 4-2. Project Requirements and YMRP Acceptance Criteria Applicable to This Model Report 
Requirement 
Numbera Requirement Titlea 
10 CFR Part 63 
Link 
YMRP Acceptance 
Criteriab 
PRD-002/T-015 Requirements for Performance Assessment 10 CFR 63.114 
[DIRS 156605] 
2.2.1.3.8.3, criteria 1 to 4 
a from Canori and Leitner (2003 [DIRS 166275]). 
b from NRC (2003 [DIRS 163274]). 
YMRP=Yucca Mountain Review Plan, Final Report 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 4-2 November 2004 
The applicable acceptance criteria in the YMRP (NRC 2003 [DIRS 163274], Section 2.2.1.3.8.3) 
are given below. How they are addressed by this report is described in Section 8.4. 
Acceptance Criterion 1: System Description and Model Integration Are Adequate. 
(1) Total system performance assessment adequately incorporates important 
design features, physical phenomena, and couplings, and uses consistent and 
appropriate assumptions, throughout the flow paths in the SZ abstraction 
process; 
(2) The description of the aspects of hydrology, geology, geochemistry, design 
features, physical phenomena, and couplings, that may affect flow paths in 
the SZ, is adequate. Conditions and assumptions in the abstraction of flow 
paths in the SZ are readily identified, and consistent with the body of data 
presented in the description; 
(4) Boundary and initial conditions used in the total system performance 
assessment abstraction of flow paths in the SZ are propagated throughout its 
abstraction approaches. For example, abstractions are based on initial and 
boundary conditions consistent with site-scale modeling and regional 
models of the Death Valley ground-water flow system; 
(5) Sufficient data and technical bases to assess the degree to which features, 
events, and processes have been included in this abstraction are provided; 
(6) Flow paths in the SZ are adequately delineated, considering natural site 
conditions; 
(7) Long-term climate change, based on known patterns of climatic cycles 
during the Quaternary period, particularly the last 500,000 years, and other 
paleoclimate data, are adequately evaluated; 
(8) Potential geothermal and seismic effects on the ambient SZ flow system are 
adequately described and accounted for; 
(9) The impact of the expected water table rise on potentiometric heads and 
flow directions, and consequently on repository performance, is adequately 
considered; and 
(10) Guidance in NUREG1297 and NUREG1298 (Altman, et al., 1988a,b), or 
other acceptable approaches for peer review and data qualification is 
followed. 
Acceptance Criterion 2: Data Are Sufficient for Model Justification. 
(1) Geological, hydrological, and geochemical values used in the license 
application to evaluate flow paths in the SZ are adequately justified. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 4-3 November 2004 
Adequate descriptions of how the data were used, interpreted, and 
appropriately synthesized into the parameters are provided; 
(2) Sufficient data have been collected on the natural system to establish initial 
and boundary conditions for the abstraction of flow paths in the SZ; 
(3) Data on the geology, hydrology, and geochemistry of the SZ used in the 
total system performance assessment abstraction are based on appropriate 
techniques. These techniques may include laboratory experiments, sitespecific 
field measurements, natural analogue research, and process-level 
modeling studies. As appropriate, sensitivity or uncertainty analyses, used 
to support the U.S. Department of Energy total system performance 
assessment abstraction, are adequate to determine the possible need for 
additional data; and 
(4) Sufficient information is provided to substantiate that the proposed 
mathematical groundwater modeling approach and proposed model(s) are 
calibrated and applicable to site conditions. 
Acceptance Criterion 3: Data Uncertainty Is Characterized and Propagated Through the 
Model Abstraction. 
(1) Models use parameter values, assumed ranges, probability distributions, and 
bounding assumptions that are technically defensible, reasonably account 
for uncertainties and variabilities, and do not result in an underrepresentation 
of the risk estimate; 
(2) Uncertainty is appropriately incorporated in model abstractions of 
hydrologic effects of climate change, based on a reasonably complete search 
of paleoclimate data; 
(3) Uncertainty is adequately represented in parameter development for 
conceptual models, process-level models, and alternative conceptual 
models, considered in developing the abstraction of flow paths in the SZ. 
This may be done either through sensitivity analyses or through use of 
conservative limits. For example, sensitivity analyses and/or similar 
analyses are sufficient to identify SZ flow parameters that are expected to 
significantly affect the abstraction model outcome; and 
(4) Where sufficient data do not exist, the definition of parameter values and 
conceptual models is based on appropriate use of expert elicitation, 
conducted in accordance with NUREG1563 (Kotra, et al., 1996 
[DIRS 100909]). If other approaches are used, the U.S. Department of 
Energy adequately justifies their uses. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 4-4 November 2004 
Acceptance Criterion 4: Model Uncertainty Is Characterized and Propagated Through the 
Model Abstraction. 
(1) Alternative modeling approaches of features, events, and processes are 
considered and are consistent with available data and current scientific 
understanding, and the results and limitations are appropriately considered 
in the abstraction; 
(2) Conceptual model uncertainties are adequately defined and documented, and 
effects on conclusions regarding performance are properly assessed. For 
example, uncertainty in data interpretations is considered by analyzing 
reasonable conceptual flow models that are supported by site data, or by 
demonstrating through sensitivity studies that the uncertainties have little 
impact on repository performance; 
(3) Consideration of conceptual model uncertainty is consistent with available 
site characterization data, laboratory experiments, field measurements, 
natural analogue information and process-level modeling studies; and the 
treatment of conceptual model uncertainty does not result in an 
under-representation of the risk estimate; and 
(4) Appropriate alternative modeling approaches are consistent with available 
data and current scientific knowledge, and appropriately consider their 
results and limitations, using tests and analyses that are sensitive to the 
processes modeled. 
4.3 CODES, STANDARDS, AND REGULATIONS 
No codes, standards, or regulations other than those identified in the project requirements 
document (Canori and Leitner 2003 [DIRS 166275], Table 2-3) and determined to be applicable 
(Table 4-4) were used in this model report. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 5-1 November 2004 
5. ASSUMPTIONS 
A list of the assumptions used in this model report is provided in Table 5-1. The rationale and 
confirmation status for each status assumption is also provided. The upstream assumptions 
associated with the rationale below do not impact the results of the model. 
Table 5-1. Assumptions 
Number Assumption Rationale 
Confirmation 
Status 
Location in 
this Report 
1 A horizontal to vertical 
anisotropy ratio of 10:1 is 
appropriate for most of the 
hydrogeologic units in the SZ 
site-scale flow model. 
This assumption is justified by common 
usage among groundwater modelers 
including the DVRFS, Yucca Mountain, 
and Nevada Test Site (NTS); and by the 
Yucca Mountain Expert Elicitation Panel 
(CRWMS M&O 1998 [DIRS 100353], 
Table 3-2). The 10:1 ratio is the 
geometric mean of the 1:1 To 100:1 
range given by the experts 
This 
assumption 
does not 
require 
confirmation 
for LA 
submittal. 
Used 
throughout 
this report. 
2 The hydrogeologic properties 
for all units in the SZ 
site-scale flow model may be 
represented as 
homogeneous values. 
This assumption is introduced due to the 
lack of information on the areal 
heterogeneity within the SZ. The flow 
model is designed to simulate the 
groundwater flow field at a scale of many 
kilometers. For simulating flow at that 
scale, effective flow parameters are 
generally acceptable. Thus, the use of 
homogeneous properties within a 
particular flow unit is acceptable. The 
calibration process provides best fit 
parameters for the SZ model. Where 
appropriate, additional zones or 
parameters are supplied to represent 
spatial differences in hydrogeology. 
These zones are justified in the sections 
in which they are used (see, for example, 
Sections 6.5.3.1 and 6.5.3.4). 
This 
assumption 
does not 
require 
confirmation 
for LA 
submittal. 
Used 
throughout 
this report. 
DVRFS = Death Valley Regional Flow System; LA=license application; NTS = Nevada Test Site; SZ=saturated 
zone. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 5-2 November 2004 
INTENTIONALLY LEFT BLANK
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-1 November 2004 
6. MODEL DISCUSSION 
6.1 MODELING OBJECTIVES 
The purpose of the SZ site-scale flow model is to describe the steady-state flow of groundwater 
as it moves from the water table below the repository, through the SZ, and to the accessible 
environment. The flow model describes the SZ advective processes that control the movement 
of groundwater and the movement of dissolved radionuclides and colloidal particles that might 
be present. 
The current SZ site-scale flow model was developed in support of the TSPA-LA. The current 
model was built upon the model used for the TSPA-SR (CRWMS M&O 2000 [DIRS 153246]) 
but includes a number of modifications to (1) reflect the current understanding of the SZ flow, 
(2) enhance model validation and uncertainty analyses, and (3) incorporate new data collected 
since the TSPA-SR. Changes introduced since the TSPA-SR iteration include the following: 
 Use of field and laboratory tests (hydraulic and tracer data collected since TSPA-SR) to 
establish and confirm the conceptual model for flow, constrain model parameter 
calibration, and provide data for model validation and confidence building. 
 Use of thermal data for model validation. 
 For validation purposes, use of recently collected hydraulic and geologic data that were 
obtained from the Nye County Early Warning Drilling Program (NC-EWDP). 
This modeling analysis is a direct feed to Site-Scale Saturated Zone Transport (BSC 2004 
[DIRS 170036]) as it provides the SZ flow fields and specific discharge in transport calculations. 
6.2 FEATURES, EVENTS, AND PROCESSES CONSIDERED IN MODEL 
As stipulated in the Technical Work Plan for: Natural System - Saturated Zone Analysis Model 
Report Integration (BSC 2004 [DIRS 171421]) this model report addresses the SZ FEPs 
pertaining to SZ flow that are included (i.e., Included FEPs) for TSPA-LA (Table 6-1). SZ FEPs 
that were excluded (i.e., Excluded FEPs) for TSPA-LA are described in Features, Events, and 
Processes in SZ Flow and Transport (BSC 2004 [DIRS 170013]). Table 6-1 provides a list of 
FEPs that are relevant to this model analysis in accordance with their assignment in the LA FEP 
list (DTN: MO0407SEPFEPLA.000 [DIRS 170760]). Specific reference to the various sections 
within this document where issues related to each FEP are addressed is provided in the table. 
The detailed discussion of these FEPs, and their implementation in TSPA-LA are documented in 
the Features, Events, and Processes in SZ Flow and Transport (BSC 2004 [DIRS 170013]). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-2 November 2004 
Table 6-1. Features, Events, and Processes Included in TSPA-LA and Relevant to this Model Report 
FEP No. FEP Name 
Sections Where 
Disposition is 
Described 
Discussed in Supporting 
AMRs 
1.2.02.01.0A Fractures Sections 6.3.3, 6.5.1, 
8.3.2, 8.3.1 
Upstream Feedsa BSC 
2004 [DIRS 170014] (BSC 
2004 [DIRS 170008]) 
Corroboratingb BSC 2004 
[DIRS 170010] 
1.2.02.02.0A Faults Sections 6.3, 6.5, 6.3.2, 
6.5.3.1; Table 6-6 
Upstream Feedsa BSC 
2004 [DIRS 170008] 
Corroboratingb BSC 2004 
[DIRS 170010] 
1.3.07.02.0A Water table rise affect SZ Section 6.4.5.1 Upstream Feedsa BSC 
2004 [DIRS 170009] 
2.2.03.01.0A Stratigraphy Sections 6.5.3.1, 
6.5.3.4, 6.5.3, 6.3.2 
Upstream Feedsa BSC 
2004 [DIRS 170008] ; 
Corroboratingb BSC 2004 
[DIRS 170014] BSC 2004 
[DIRS 170010] 
2.2.03.02.0A Rock properties of host rock 
and other units 
Sections 6.5.3, 6.5.3.4,; 
Table 6-6 
Upstream Feedsa BSC 
2004 [DIRS 170008] 
Corroboratingb BSC 2004 
[DIRS 170010] 
2.2.07.12.0A Saturated groundwater flow in 
the geosphere 
Sections 6.2, 6.3, 6.3.1, 
6.3.2, 6.3.2.7, 6.3.2.10, 
6.5; Figure 6-1; A-6.7.6, 
A-6.7.7, A-6.7.8, A- 
6.7.9, and A-6.7.11 
Upstream Feedsa BSC 
2004 [DIRS 170015] ; 
Corroboratingb BSC 2004 
[DIRS 170014] BSC 2004 
[DIRS 170010] 
2.2.07.13.0A Water-conducting features in 
the SZ 
Sections 6.3, 6.3.2, 6.5, 
6.5.3.4; Figure 6-4; 
Table 6-6 
Upstream Feedsa BSC 
2004 [DIRS 170008] ; 
Corroboratingb BSC 2004 
[DIRS 170014] BSC 2004 
[DIRS 170010] 
2.2.07.15.0A Advection and dispersion in 
the SZ 
Sections 6.3-6.8, 8 Upstream Feedsa BSC 
2004 [DIRS 170015] 
Corroboratingb BSC 2004 
[DIRS 170010] 
2.2.08.01.0A Chemical Characteristics Section A-7.1.2; Tables 
A-10, A-11 
Corroboratingb BSC 2004 
[DIRS 170042], BSC 2004 
[DIRS 170036] 
2.2.10.03.0A Natural geothermal effects on 
flow in the SZ 
Sections 6.5.3.7, 7.4 This report 
Upstream Feedsa NA 
Corroborating NA 
a Aspects of the SZ FEPs screening position adopted in this report are a result of SZ analyses 
performed in a directly upstream SZ model or analyses. N/A indicates there are no upstream feeds. 
b Corroborating-SZ analysis or model report that indirectly supports the FEP topic. 
AMRs = analysis model reports; FEP = features, events, and processes; SZ = saturated zone. 
6.3 CONCEPTUAL MODEL 
The SZ site-scale flow model presented in this section describes our current state of knowledge 
of the saturated flow system. The original hydrogeologic framework model (HFM-19) used in 
the base case model is shown in Section 6.5.3.2 (see Figure 6-28). This figure displays a 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-3 November 2004 
three-dimensional representation of the hydrogeologic units used in the HFM and is useful in 
visualizing the region modeled in this report. Additional information that corroborates the base 
case model is presented in Appendix A. 
The general conceptual model of SZ flow in the SZ site-scale flow model area is that 
groundwater flows southerly from recharge areas of higher precipitation at higher elevations 
north of Yucca Mountain, through the Fortymile Wash and toward the Amargosa Desert. Within 
the site-scale model area, recharge occurs from infiltration of both precipitation and flood-flows 
from Fortymile Wash and its tributaries. In the southeastern part of the model area (within the 
Ash Meadows groundwater basin), considerable flows enter and exit the area in the lower 
carbonate aquifer system (BSC 2004 [DIRS 170015], Section 6.2). This aquifer system is 
believed to underlie much of the Alkali Flat-Furnace Creek groundwater basin based on 
inferences from Death Valley regional groundwater flow data as explained below. However, the 
flow patterns of groundwater in this area and their relationship to flow in the Ash Meadows flow 
system are poorly understood. Outflow from the SZ site-scale flow model area mostly occurs 
across the southern boundary of the model. The boundary conditions on the southern boundary 
include discharge by irrigation wells in the Amargosa Farms area. 
6.3.1 Key Features 
Within the boundaries of the site-scale flow model area, there are several components that 
strongly affect the local flow system and potential radionuclide transport. Those are: 
 Solitario Canyon fault 
 Recharge on Yucca Mountain 
 Crater Flat tuff hydrogeologic units 
 Shallow alluvial aquifer of Fortymile Wash 
 Regional carbonate aquifer. 
The Solitario Canyon fault is important because it provides a fast vertical flow path from the 
surface to the SZ. It also can provide a barrier for water flowing laterally under Yucca Mountain 
that originated in Crater Flat. Recharge to the SZ is important because the transport time of 
potential radionuclides is directly dependent on it. The Crater Flat tuffs, particularly the Bullfrog 
unit, are likely to be the most permeable hydrogeologic units near the repository and, thus, are 
the most likely paths for potential radionuclide transport. The shallow alluvial aquifer in 
Fortymile Wash is important because it both contains the likely flow paths for fluid leaving the 
repository area and has desirable retardation characteristics for many radionuclides. The 
regional carbonate aquifer underlies the likely flow area for fluid leaving the repository area. 
This aquifer also provides an upward gradient that keeps the flow lines shallow and, effectively, 
isolates the local Yucca Mountain system from the regional carbonate aquifer. 
Hydrochemical studies conducted at and near Yucca Mountain over the last 25 years are 
summarized in Appendix A. The appendix provides an analysis of groundwater recharge rates, 
flow directions and velocities, and mixing proportions of water from different source areas based 
on analyses of the geochemistry and isotopic constraints. It also provides an evaluation of data 
to determine chemical reactions in the groundwater system, the evolution of groundwater as it 
moves along the flow pathway, groundwater-mixing relationships, and chemical controls on 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-4 November 2004 
strontium and uranium. The appendix also examines groundwater residence times based on 
corrected 14C ages and evaluates water/rock interactions to provide a basis for the 14C age 
corrections. The appendix provides a comparison of patterns of groundwater movement outlined 
by the SZ flow model with flow patterns inferred strictly from hydrochemical and isotopic data. 
In this way, the analysis documented in the appendix provides an independent means of 
corroborating the SZ site-scale flow model. 
The HFM is a conceptual model providing a three-dimensional interpretation of the 
hydrostratigraphic unit locations and structure within the site-scale SZ flow and transport model 
domain for use in the SZ flow and transport numerical models. The HFM does not provide any 
hydraulic parameter, rather it provides a conceptualization of hydrogeologic units which serves 
as the basis for assigning upper and lower bounds for hydraulic parameters used in flow model 
calibration. 
6.3.2 Components of the Base Case Conceptual Model 
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 (one million years (refers to age)) from 
a series of calderas located a few to several tens of kilometers to the north (Sawyer et al. 1994 
[DIRS 100075]). Yucca Mountain itself extends southward from the Pinnacles Ridge toward the 
Amargosa Desert, where the tuffs thin and pinch out beneath the alluvium (Figure 6-1). 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 [DIRS 100027], pp. 6 to 7). 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 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 6-3). Topography is highly variable 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. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-5 November 2004 
Source: DTN: GS991208314221.001 (DIRS 145263). 
NOTE: The blue rectangle is the boundary of the numerical model for SZ flow and transport. 
SZ = saturated zone; UTM = Universal Transverse Mercator. 
Figure 6-1. Important Physiographic Features Near Yucca Mountain Including Boundaries of the SZ 
Site-Scale Flow Model 
The boundaries of the numerical models for SZ flow and transport are labeled as the SZ 
site-scale flow boundary in Figure 6-1. The domain was selected to be: (1) coincident with grid 
cells in the DVRFS model (DTN: GS960808312144.003 [DIRS 105121]) such that the base of 
the site model is consistent with the base of the regional model (2,750 m below a smoothed 
version of the potentiometric surface); (2) sufficiently large to reduce the effects of boundary 
conditions on estimating permeability values and calculated flow fields at Yucca Mountain; 
(3) sufficiently large to assess groundwater flow at distances beyond the 18-km compliance 
boundary from the repository area; (4) small enough to minimize the model size for 
computational uses; (5) thick enough to include part of the regional Paleozoic carbonate aquifer; 
and (6) large enough to include borehole control in the Amargosa Desert at the southern end of 
the modeled area. The hydrogeologic setting of the SZ flow system in the vicinity of Yucca 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-6 November 2004 
Mountain was summarized by Luckey et al. (1996 [DIRS 100465], p. 13). Yucca Mountain is 
part of the Alkali Flat-Furnace Creek subbasin of the Death Valley groundwater basin, as 
described by Waddell (1982 [DIRS 101062], pp. 15 to 16). Discharge within the subbasin 
occurs at Alkali Flat (Franklin Lake Playa) and, possibly, Furnace Creek in Death Valley 
(Figure 6-1). 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 [DIRS 100465], p. 13). 
6.3.2.1 Groundwater Occurrence and Flow 
As described by Luckey et al. (1996 [DIRS 100465], p. 17), the Tertiary volcanic section at 
Yucca Mountain consists of a series of ash flow and bedded ash fall tuffs that contain minor 
amounts of lava and flow breccia. Individual ash flow tuffs may be several hundred meters 
thick, whereas bedded ash fall tuffs generally are less than a few tens of meters thick. Ash flow 
tuffs range from nonwelded to densely welded, and the degree of welding varies both 
horizontally and vertically in a single flow unit. Nonwelded ash flow tuffs, when unaltered, have 
moderate to low matrix permeability but high porosity. Permeability is decreased by secondary 
alteration, and fractures are infrequent and often closed in the low-strength nonwelded tuffs. 
Consequently, these rocks generally constitute laterally extensive SZ confining units in the 
Yucca Mountain area. The properties of partly welded tuffs vary between those of fractured, 
welded tuffs and those of altered, nonwelded tuffs. The densely welded tuffs generally have 
minimal primary porosity and water-storage capacity, but they can be highly fractured. Where 
interconnected, fractures can easily transmit water, and highly fractured units function as 
aquifers. In general, the bedded ash fall tuffs have high primary porosity and can store large 
amounts of water. Their matrix permeability is moderate to low, depending on the degree of 
alteration. North of Yucca Mountain the Claim Canyon caldera have been the subject of thermal 
alteration. The bedded ash fall tuffs generally function as confining units, at least when 
compared to less porous but densely fractured ash flow tuffs. Lavas, flow breccias, and other 
minor rock types are neither thick nor widely distributed in the Yucca Mountain area. Their 
hydraulic properties probably are as variable as the properties of the ash flow tuffs, but the 
relatively limited spatial distribution of these minor rock types makes them generally 
unimportant to the hydrology of Yucca Mountain. 
Luckey et al. (1996 [DIRS 100465], p. 17) state that even fractured tuffs and lavas may not 
easily transmit water because lithostatic loading keeps the fractures closed. In addition, where 
volcanic glass has been partly replaced by zeolites and clays, particularly in the originally glassy 
nonwelded tuffs, these secondary minerals substantially decrease permeability and slow 
groundwater flow through the rock. The degree of alteration can affect the water-transmitting 
characteristics of the volcanic sequence. Alteration, particularly in the Calico Hills Formation, 
increases toward the north of Yucca Mountain and probably accounts for the apparent decrease 
in hydraulic conductivity to the north. Alteration also tends to increase with depth and is 
pervasive below the Calico Hills Formation. 
Fractures vary in length, orientation, connectivity, aperture width, and amounts and types of 
coatings, all of which may affect the flow of water. The physical parameters of fractures are 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-7 November 2004 
characterized by outcrop mapping, borehole logging, and mapping in the Exploratory Studies 
Facility. In the UZ, seeps of water have not been observed in outcrop mapping or in mapping in 
the Exploratory Studies Facility. 
Fractures at Yucca Mountain originated as a result of initial cooling of the volcanic deposits and 
as a result of tectonic activity. For example, in the Tiva Canyon welded hydrologic unit, two sets 
of vertically orientated cooling fractures were observed dipping nearly vertically and striking 
towards the northwest and northeast. A third set of tectonic joints commonly abuts the cooling 
joints, and these three sets of joints form an orthogonal, three-dimensional network. An 
extensive discussion of fractures in the Yucca Mountain area is presented in the Yucca Mountain 
Site Description (BSC 2004 [DIRS 169734], Section 3.5). 
Fracture aperture characteristics are poorly known from direct observation, and for modeling, 
reliance is placed on indirect effects such as changes in air and water permeability. In general, 
the stress due to overburden loading across high-angle fractures will be less than across 
low-angle fractures, resulting in higher vertical than horizontal permeability. Stratification 
effects will also be present in many units. This will tend to have the opposite effect; that is, the 
horizontal permeability will be larger than the vertical permeability. 
The volcanic rocks consist of alternating layers of welded and nonwelded ash flow and ash fall 
(bedded) tuff deposits. Each of the ash flow units is underlain by an associated bedded tuff 
layer. The ash flow units vary in degree of welding (or recrystallization) with the maximum 
welding generally found near the center of the flow, where heat was retained the longest, and the 
degree of welding decreasing upward and downward toward the flow boundaries. 
The welded units typically have low matrix porosities and high fracture densities, whereas the 
nonwelded and ash fall have relatively higher matrix porosities and lower fracture densities. The 
fracture density is correlated with the degree of welding of the volcanic rocks. 
Where glassy tuff has been saturated for long periods (e.g., beneath the water table), the original 
glassy material generally has been altered to zeolite or clay minerals. Such alteration does not 
affect porosity greatly because it does not fill the pore spaces, but the permeability of the rocks is 
greatly reduced by alteration of the connections between the pore spaces. Alteration of silica to 
zeolites or clay minerals is not an important factor in densely welded zones because cooling 
fractures dominate permeability. 
The SZ flow system to the south of Yucca Mountain transitions from a fractured tuff aquifer to a 
valley-fill (alluvium) aquifer before reaching the approximately 18-km performance compliance 
boundary at the southern boundary of the Nevada Test Site (NTS). Underlying Crater Flat is a 
thick sequence of alluvium, lavas, and tuffs that have 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. Characterization of the 
valley-fill system was conducted just outside the southwest corner of NTS at the Alluvial Testing 
Complex (ATC), which is the site of well NC-EWDP-19D/D1. Multiple-well hydraulic tests, 
single-well hydraulic tests, and tracer tests were conducted in NC-EWDP-19D/D1. This test 
well location is shown Figure 7-1. These tests indicated producing zones with permeabilities 
consistent with other alluvial systems (1 to 10  1012 m2) interbedded with lower permeability 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-8 November 2004 
(1015 m2) clay-rich zones. In addition to flow in the volcanic rocks and alluvium in the SZ, 
groundwater also flows in the carbonate rocks of the lower carbonate aquifer. 
In general, it is believed that the matrix porosity of the ancient marine limestones and dolomites 
of the lower carbonate aquifer is negligible (Winograd and Thordarson 1975 [DIRS 101167], 
p. C14), and that the large discharge from that aquifer system at Ash Meadows is due to flow 
through solution-enlarged fractures and along faults (Dudley and Larson 1976 [DIRS 103415], 
pp. 5 and 9). One borehole, UE-25 p#1 (labeled as P#1 in Figure 6-2), penetrates the lower 
carbonate aquifer near Yucca Mountain. Another deep well, NC-EWDP-2DB was completed in 
the carbonate aquifer as part of the NC-EWDP. These deep wells helped improve the 
understanding of hydrologic conditions in the aquifers, including the deep carbonate aquifer, and 
helped to confirm the direction and magnitude of groundwater flow in that aquifer. Large 
groundwater volumetric flow has been modeled in the carbonate aquifer by DAgnese et al. 
(1997 [DIRS 100131], Figures 46 to 47, p. 90) in the Death Valley regional groundwater flow 
model within the southern part of the site-scale flow model. These results are discussed in 
Section 6.3.2.4. 
6.3.2.2 Hydrologic Features 
The HFM for the SZ site-scale flow model (HFM-19) (BSC 2004 [DIRS 170008], Section 6.3.3) 
represents faults and other hydrogeologic features (Figure 6-3) such as zones of hydrothermal 
alteration that affect SZ flow. Information on faults includes fault trace maps, which show both 
faults on cross sections and locations where faults intersect the land surface. Faults in the model 
area dip at various angles, but most are high-angle faults. Faults deemed important to flow near 
Yucca Mountain are modeled explicitly in the numerical SZ site-scale flow model. Given 
software constraints and the numerical flow model resolution, faulting in the area was simplified 
in the numerical model, and the faults were treated as vertical features. Section 6.5.3.1 discusses 
how these features were constructed in the HFM. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-9 November 2004 
C-Wells 
P#1 
WT-1
H-4 
WT-2
WT#17 
H-3 WT#13 
WT#15 
a#3 
J-11 
WT#6 
G-2 
VH-2 
VH-1 
JF-3 
J-12 
J-13 
WT#3 
WT#12 
WT-11 
WT-10 
WT-7 
H-6 
H-5 
H-1 
UZ-14 
WT#16 
b#1 
- Numbers are preceded by UE-25 or USW designations 
Large, moderate, and small gradient areas at Yucca Mountain - - - - - - - 
Source: Tucci and Burkhardt (1995 [DIRS 101060], Figures 2, 4, and 5). 
Figure 6-2. Potentiometric Surface Map and Gradient Areas Developed Using WaterLevel Data 
from 1993 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-10 November 2004 
Source: DTN: GS991208314221.001 (DIRS 145263) (Tertiary Faults). 
NOTE: The geographic coordinates and the name of the different geologic features shown in this figure are the 
results of interpretation of the geologic map, including geologic cross-sections, and lithostratigraphic and 
structural data from boreholes as it is described in detail in BSC (2004 [DIRS 170008]). The conversion of 
the geographic coordinates was done using standard Geographic System Information (GIS) functions. 
See BSC (2004 [DIRS 170008], Figure 6-3) for an example showing both, the latitude/longitude and UTM 
coordinates of the site-scale model and some of the features shown in Figure 6-37. 
UTM = Universal Transverse Mercator. 
Figure 6-3. Location of Faults in the Yucca Mountain Region 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-11 November 2004 
6.3.2.3 Flow Field 
Using the potentiometric surface map (Figure 6-4) and the supposition that hydraulic 
conductivity is horizontally isotropic, the general direction of groundwater flow within the SZ 
site-scale flow and transport model area can be deduced as being from north to south. Under this 
supposition, the direction of flow is perpendicular to the waterlevel contours. Under the BSC 
(2004 [DIRS 170008], Section 6.3.6) interpretation of the waterlevel data, the water table 
exhibits a steep gradient throughout the northern part of the model area (north of the repository) 
and the contours curve southward to the west of Crater Flat. 
Several faults (Figure 6-4) are interpreted as barriers to groundwater flow, as indicated by offsets 
of contours where they cross faults. This interpretation is supported only by field data at the 
Solitario Canyon fault, west of the repository, which is interpreted as causing a differential of 
about 45 m (148 ft) in the potentiometric surface. In Crater Flat and on the southern part of 
Yucca Mountain, the flow direction is nearly easterly toward Fortymile Wash. A more detailed 
waterlevel map of the immediate vicinity of Yucca Mountain (Figure 6-2) indicates that flows 
from the west and east converge at Fortymile Wash and turn southward toward the Amargosa 
Desert. The cause of the easterly gradient in Crater Flat and southern Yucca Mountain is not 
evident, but it suggests that a groundwater barrier exists near the northern margin of the 
Amargosa Desert. In any event, the potentiometric surface upgradient of the 725-m (2,379-ft) 
contour and the U.S. Highway 95 fault appears to have little north-south flow over an area of 
about 259 km2 (100 mi2). Note that Figure 6-2 is a waterlevel map using 1993 data. Newer 
data do not contradict any of the discussion of this paragraph. 
As discussed in Section 6.3.2.5, the potentiometric level in well UE-25 p#1, which penetrates the 
lower carbonate aquifer, is about 752 m (2,467 ft), 21 m (69 ft) higher than in nearby wells 
tapping the lower volcanic aquifer. This result indicates a potential for upward flow from the 
lower carbonate aquifer; however, other lines of evidence suggest that such flow is small. The 
direction of flow and hydraulic gradient cannot be determined from a single well; however, 
regional relationships suggest that the general direction of flow in the lower carbonate aquifer 
should be southerly to southeasterly in the SZ site-scale flow model domain (NRC 1998 
[DIRS 107770], p. 109). South of the site-scale model domain, there is geochemical evidence 
for a westward component of flow in the carbonate aquifer (Appendix A). 
Most monitoring wells in the Yucca Mountain area show little variation in water level over time 
(Luckey et al. 1996 [DIRS 100465], p. 29). In contrast, water levels in the heavily pumped 
Amargosa Farms area have declined substantially since intensive irrigation development began 
in the 1950s. Kilroy (1991 [DIRS 103010], p. 18) reported a water level decline of as much as 
9 m (30 ft) by 1987, and La Camera and Locke (1997 [DIRS 103011], Figure 4) show an 
additional decline of about 3.4 m (11 ft) through 1996 at well AD-5, about 14 km (8.7 mi) 
southwest of the Amargosa Valley. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-12 November 2004 
Source: DTN: GS991208314221.001 (DIRS 145263) (Tertiary faults); GS00050812332.001 (DIRS 149947) 
(Water-level contours.) USGS (2001 (DIRS 154625), Figure 1-2). 
NOTE: The inferred groundwater flow directions are based on Assumption 1 in Appendix A (see Table A5-1). 
The circular areas outlined in red near the Calico Hills in the northeast corner of the map are zones of 
hydrothermal alteration associated with granitic intrusions (Table 6-17). The semicircular area along the 
central northern portion of the map is the southern boundary of the Claim Canyon caldera (Table 6-17). 
The other red lines are selected faults; blue crosses indicated the location of hydraulic head 
measurements. Potentiometric Surface and Inferred Flow Directions are indicated by light blue arrows. 
UTM = Universal Transverse Mercator projection system of coordinates. 
Figure 6-4. Potentiometric Surface and Inferred Flow Directions for Yucca Mountain and Vicinity 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-13 November 2004 
6.3.2.4 Large, Moderate, and Small Hydraulic Gradients 
Three distinctive hydraulic gradients of the potentiometric surface at Yucca Mountain are 
recognized: (1) a large hydraulic gradient of 0.13 between waterlevel altitudes of 1,030 m 
(3,380 ft) and 750 m (2,460 ft) at the northern end of Yucca Mountain, (2) a moderate hydraulic 
gradient of 0.05 west of the crest of Yucca Mountain, and (3) a small hydraulic gradient of 
0.0001 to 0.0003 extending from Solitario Canyon to Fortymile Wash. These gradients have 
been portrayed on detailed potentiometric surface maps presented by Ervin et al. 
(1994 [DIRS 100633]), and Tucci and Burkhardt (1995 [DIRS 101060]), as well as on the maps 
with large contour intervals compiled by DAgnese et al. (1997 [DIRS 100131]). The large 
contour-interval maps do not portray the small or moderate gradients adequately because of 
limitations imposed by contour intervals; however, the large gradient is recognizable on all of 
these maps. 
Luckey et al. (1996 [DIRS 100465]) present detailed descriptions of these gradient features and 
discuss interpretations of their causes. The large hydraulic gradient has been the subject of 
numerous theories and could be the results of the Claim Canyon caldera and their associated 
thermal alteration. The large gradient is discussed in Luckey et al. (1996 [DIRS 100465], pp. 21 
to 25): 
 The gradient is the result of flow through the upper volcanic confining unit, which is 
nearly 300 m (984 ft) thick near the large gradient. This large thickness of low 
permeability material creates a barrier to flow that causes water to back up behind it, 
raising hydraulic head to the north, and leading to the large gradient. 
 The gradient represents a semi-perched system in which flow in the upper and lower 
aquifers is predominantly horizontal, whereas flow in the upper confining unit would be 
predominantly vertical. In this scenario, the large hydraulic gradient is a manifestation 
of water leaking out of the upper aquifer, through the confining unit, and into the lower 
aquifer. Farther south, water has drained out of the perched aquifer and now only the 
lower heads of the deeper aquifer are measured. The difference in heads between the 
northern-perched water levels and the southern deeper aquifer levels appears as a large 
hydraulic gradient. 
 The gradient represents a drain down a buried fault from the volcanic aquifers to the 
lower carbonate aquifer. In this case water levels drop quickly as the feature is 
approached from the north much in the same way water levels drop into the cone of 
depression caused by a pumping well. In this case, the feature is linear; the result is a 
region of steep hydraulic gradient rather than a cone of depression around a single well. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-14 November 2004 
 The gradient represents a spillway in which a fault marks the effective northern limit of 
the lower volcanic aquifer. In this scenario, water flows more readily in lower volcanic 
aquifer, which is located south of the LHG. This effectively drains off the high 
hydraulic heads and established a lower water level. North of this location, the lower 
permeabilities create a barrier to flow that keeps water levels high. 
 The large gradient results from the presence at depth of the Eleana formation, a part of 
the Paleozoic upper confining unit, which overlies the lower carbonate aquifer in much 
of the Death Valley region. The Eleana formation is absent at Borehole UE-25 p#1 at 
Yucca Mountain, which penetrated the lower carbonate aquifer directly beneath the 
lower volcanic confining unit. 
The cause of the moderate hydraulic gradient is less controversial than that of the large gradient, 
and Luckey et al. (1996 [DIRS 100465], p. 25) suggest that the Solitario Canyon fault and its 
splays function as a barrier to flow from west to east due to the presence of low-permeability 
fault gouge or to the juxtaposition of more permeable units against less permeable units. 
The small hydraulic gradient occupies most of the repository area and the downgradient area 
eastward to Fortymile Wash. Over a distance of 6 km (3.7 mi), the hydraulic head declines only 
about 2.5 m (8.2 ft) between the crest of Yucca Mountain and Fortymile Wash. The small 
gradient could indicate highly transmissive rocks, little groundwater flow in this area, or a 
combination of both causes (Luckey et al. 1996 [DIRS 100465], p. 27). 
The potentiometric map (BSC 2004 [DIRS 170009], Section 6.4), which includes head data from 
the recently drilled NC-EWDP boreholes, indicates that the small hydraulic gradient extends 
southward to an east-west fault located approximately along U.S. Highway 95 (see BSC 2004 
[DIRS 170009], Figure 6-1). 
6.3.2.5 Vertical Gradients 
Information on vertical hydraulic gradients in the SZ is available near Yucca Mountain, from the 
Nye County Early Warning Wells (BSC 2004 [DIRS 170009]), and from Kilroy (1991 
[DIRS 103010]) for wells in the Amargosa Desert. The following discussion of vertical 
gradients is extracted from Luckey et al. (1996 [DIRS 100465], pp. 27 to 29) and BSC (2004 
[DIRS 170009], Sections 6.3.1 and 7.1.1). 
BSC (2004 [DIRS 170009], Section 6.3.2)report on potentiometric level measurements in 
multiple depth intervals in 17 boreholes at Yucca Mountain. Differences in potentiometric levels 
at different depth intervals in the same borehole ranged from as little as 0.10 m (0.33 ft) in 
Borehole USW H-4 to as much as 54.7 m (180 ft) in USW H-1 (BSC 2004 [DIRS 170009], 
Table 6-4). The largest differences were between the lower carbonate aquifer or the adjoining 
lowermost lower volcanic confining unit and the overlying lower volcanic aquifer and at the well 
NC-EWDP-1DX location along U.S. Highway 95 south of Crater Flat. Between the upper part 
of the lower volcanic confining unit and the lower volcanic aquifer, the differences in 
potentiometric levels generally were 1 m (3.3 ft) or less. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-15 November 2004 
Potentiometric levels generally were higher in the lower intervals of the volcanic rocks than in 
the upper intervals, indicating a potential for upward groundwater movement. However, at seven 
boreholes (USW G-4, USW H-1, USW H-6, UE-25 J-13, NC-EWDP-1DX, NC-EWDP-3S, and 
UE-25 b#1), potentiometric levels in the volcanic rocks were slightly higher in the uppermost 
intervals than in the next lower intervals. Overall, it appears that an upward gradient between the 
lower and upper volcanic aquifer is maintained at these locations nearest Yucca Mountain (USW 
G-4, USW H-1, USW H-6, and UE-25 b#1). Away from Yucca Mountain the direction of the 
vertical hydraulic gradient varies from location to location. For example, at locations UE-25 
J-13, NC-EWDP-1DX, and NC-EWDP-3S, there is a consistent downward gradient in the upper 
portion of the volcanic units. For wells in the lower Fortymile Wash, such as 
NC-EWDP-2D/-2DB, NC-EWDP-4PA/-4PB, NC-EWDP-9SX, NC-EWDP-12PA/-12PB/-12PC, 
and NC-EWDP-19P/-19D, the gradient is consistently upward. 
Potentiometric levels in the Paleozoic carbonate aquifer in Borehole UE-25 p#1 are about 
752 m (2,467 ft), or about 21 m (69 ft) higher than levels in the overlying lower volcanic aquifer. 
The potentiometric levels in the Paleozoic carbonate aquifer in borehole NC-EWDP-2DB is 
about 7.2 m higher than the overlying volcanic unit at NC-EWDP-2D. A potential for upward 
groundwater movement from the Paleozoic rocks to the volcanic rocks was, therefore, indicated. 
Because of the large difference in potentiometric levels in these two aquifers, they seem to be 
hydraulically separated (Luckey et al. 1996 [DIRS 100465], p. 28). Testing at the C-wells 
complex in 1984 suggested a hydraulic connection between the lower volcanic aquifer and the 
carbonate aquifer; however, testing in 1995 and 1996, using more reliable waterlevel 
measurement equipment, did not confirm the hydraulic connection (Luckey et al. 1996 
[DIRS 100465], p. 28). 
In borehole UE-25 p#1, the lowermost 70 m (230 ft) of the older tuffs (lower volcanic confining 
unit) had potentiometric levels similar to those in the carbonate aquifer, indicating a hydraulic 
connection between the lowermost part of the lower volcanic confining unit and the carbonate 
aquifer. Such a connection could be expected in the hanging-wall rocks adjacent to a fault; and, 
this type of connection is supported by calcification of the basal tuffs in the borehole. The 
remaining 237 m (778 ft) of the lower volcanic confining unit had a potentiometric level similar 
to that of the lower volcanic aquifer (Luckey et al. 1996 [DIRS 100465], p. 28). The upward 
hydraulic gradient observed in wells NC-EWDP-2D/-2DB supports the conceptual model that 
water levels in the carbonate aquifer are higher than in the overlying volcanic units throughout a 
large portion of the SZ site-scale flow model area (BSC 2004 [DIRS 170009], Section 7.1.1). 
No obvious spatial patterns in the distribution of vertical hydraulic gradients around Yucca 
Mountain are apparent; however, some generalizations can be made as to the distribution of 
potentiometric levels in the lower sections of the volcanic rocks. Potentiometric levels in the 
lower volcanic confining unit are relatively high (altitude greater than 750 m [2,460 ft]) in the 
western and northern parts of Yucca Mountain and are relatively low (altitude about 730 m 
[2,395 ft]) in the eastern part of Yucca Mountain. Based on potentiometric levels that were 
measured in borehole UE-25 p#1 and NC-EWDP-2D/-2DB, the potentiometric levels in the 
lower volcanic confining unit in boreholes USW H-1, USW H-3, USW H-5 and USW H-6 may 
reflect the potentiometric level in the carbonate aquifer. Boreholes UE-25 b#1 and USW G-4 do 
not seem to fit the pattern established by the other boreholes. These two boreholes penetrated 
only 31 m (102 ft) and 64 m (210 ft), respectively, into the lower volcanic confining unit and had 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-16 November 2004 
potentiometric levels (about 730 m [2,395 ft]) that were similar to potentiometric levels in the 
lower volcanic aquifer. Penetration of the other four boreholes into the lower volcanic confining 
unit ranged from 123 m (403 ft) in borehole USW H-3 to 726 m (2,382 ft) in borehole USW H-1. 
Only in boreholes USW H-1, USW H-3, USW H-5, and USW H-6 are the potentiometric levels 
in the lower volcanic confining unit influenced by the potentiometric level in the carbonate 
aquifer (Luckey et al. 1996 [DIRS 100465], p. 29). 
At several wells, including USW H-1 and USW H-6, small hydraulic gradient reversals at 
several depths are observed (see BSC 2004 [DIRS 170009], Table 6-4). These small reversals 
may be explained by small-scale heterogeneities in the hydrostratigraphic units or measurement 
errors (BSC 2004 [DIRS 170009], Section 6.3.2). The confidence in the vertical hydraulic head 
differences is greatest for the locations with the largest hydraulic head differences. 
Vertical hydraulic gradients could have an important impact on the analysis of the effectiveness 
of the SZ as a barrier to radionuclide transport in that they keep the flow path from the potential 
repository in the shallow groundwater. Based on available data, a spatially extensive upward 
gradient can be inferred between the carbonate aquifer and the volcanic aquifers, which indicates 
that, at least for the immediate Yucca Mountain area, radionuclide transport would be restricted 
to the volcanic system (BSC 2004 [DIRS 170009], Section 7.1.1). 
Kilroy (1991 [DIRS 103010], pp. 11 to 16, Table 3) presents vertical gradient data for 21 nested 
piezometers, 1 well cluster, and 1 river and well pair in the Amargosa Desert area. However, 
none of these locations is within the area of the SZ site-scale model, so the results are not 
discussed in detail here. Upward gradients generally were associated with freshwater limestones, 
carbonate rock outcrops, and structural features (Kilroy 1991 [DIRS 103010], p. 16). The 
association with carbonate rocks is attributed to a hydraulic connection with the carbonate 
aquifer regional flow system and, especially, to the Spotted Range-Mine Mountain fault zone, 
which is a conduit for flow from the carbonate aquifer to the basin fill. 
6.3.2.6 Lateral Boundary Conditions 
The boundary conditions used in the SZ site-scale flow model are derived from hydraulic heads 
predicted by the DVRFS model and measured water levels (DTN: GS000508312332.001 
[DIRS 149947]). The data are used to form fixed-head boundary conditions on the lateral sides 
of the model. These fixed heads, it is meant that the heads may vary in space along the boundary 
but not in the vertical direction or with time. Because of constant vertical head, this condition 
produces no vertical flow at the boundary. This model contrasts with a known upward gradient 
in the area near well UE-25 p#1. Nevertheless, some upward gradient can be obtained away 
from the boundaries with the present boundary conditions. This is because permeability 
differences between the hydrogeologic units propagate the head for the higher permeability 
carbonate rocks farther into the model interior than the lower permeability volcanic confining 
unit overlaying the carbonate rocks. A discussion of the impact of the boundary conditions on 
predicted vertical gradients is presented in Section 6.2.1. Of special note is the southern 
boundary of the model, which is near a large number of wells in the Amargosa Valley. The 
water levels at the southern boundary reflect the influence of lower water levels caused by 
drawdown in the Amargosa Valley wells. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-17 November 2004 
Here there are a variety of measurements over the time of usage. Some of the earlier 
measurements represent predevelopment states, and the later measurements generally represent 
water levels that show the effects of pumping. The boundary conditions represent water levels 
with pumping and are described in BSC (2004 [DIRS 170015], Sections 6.5 and 6.7). (See 
Section 6.4.4 for a discussion of the water level used in this report and the other analyses that are 
available.) 
Most of the inflows to, and outflows from, the SZ site-scale flow model occur as groundwater 
flows across the lateral boundaries. The best estimates of flow rates are the cell-by-cell fluxes 
calculated by the 1997 Death Valley regional flow model. These fluxes are compiled in 
four tables (BSC 2004 [DIRS 170015], Tables 6-5, 6-6, 6-7, and 6-8) corresponding to each 
boundary of the SZ site-scale flow model. The flows are compiled by the three depth layers (0 to 
500 m [0 to 1,640 ft], 500 to 1,250 m [1,640 to 4,100 ft], and 1,250 to 2,750 m [4,100 to 9,020 ft] 
below the water table) of the regional flow model (DAgnese et al. 1997 [DIRS 100131], p. 75). 
The lateral boundary fluxes from the regional-scale flow model were used in the calibration of 
the SZ site-scale flow model. Lateral boundary fluxes play an important role in the SZ site-scale 
flow model. These fluxes provide some communication with the regional-scale flow model, 
which is based on a regional mass balance and calibrated to spring flow data. There are 
differences between the SZ site-scale flow model and the regional model largely due to the 
HFMs used for the two models. These differences are exacerbated because the two models also 
used different grid resolutions and methods to simulate hydrogeology. Thus it was necessary to 
average the fluxes over many grid blocks on each side of the model. Output from the regional 
flow model is linked to the SZ site-scale flow model through the calibration code PEST V5.5, 
STN: 10289-5.5-00 (Watermark Computing 2002 [DIRS 161564]). Averaged fluxes derived 
from the regional flow model were used for calibration targets in the SZ site-scale flow model 
calibration process in much the same way water levels were used for targets. (The regional flow 
model is not a direct input but is cited as the reference for the DTN for recharge and lateral 
fluxes in Table 4-1.) These targets were weighted differently based on the importance of a given 
average flux to the SZ site-scale flow model. Because of the differences in the two models, only 
general agreement regarding fluxes is expected, and obtained, between the two models. 
Consistent with the regional flow model, the bottom boundary condition of the SZ site-scale flow 
model was no-flow. Direct evapotranspiration from the water table is not considered in this 
analysis because depth to water is too great for this process to be important. The top boundary 
condition was a specified flux recharge map described in Section 6.3.2.7 and derived from the 
regional model, the UZ model and evapotranspiration studies along Forty-Mile wash. Because 
the flow model is a steady-state model, there are no boundary condition temporal variation 
requirements. 
6.3.2.7 Recharge 
The recharge to the site-scale flow model was derived from three sources (site-scale UZ model, 
regional-scale SZ model, and Fortymile Wash data) that take different forms and are combined 
into a single result (see Table 6-12 for the complete list of fluxes). Recharge from the site-scale 
UZ model (percolation flux) was taken as the flow through the base of that model, the domain of 
which includes approximately 40 km2 (19.3 mi2) that encompasses only the footprint of Yucca 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-18 November 2004 
Mountain, a very small fraction of the SZ model domain. The UZ flow model uses dual 
permeability; accordingly, the output includes fluxes for fracture and matrix flow. These data 
are combined into a total volumetric flow rate and an average percolation flux (BSC 2004 
[DIRS 170015], Table 6-4 and Figure 6-4). 
Estimates of recharge from the infiltration of surface flows in Fortymile Wash are given by 
linear reaches along the wash. Recharge estimates were interpolated to a 500-m (1,640-ft) wide 
recharge zone for most of the wash and a broader area of distributary channels in the Amargosa 
Desert (BSC 2004 [DIRS 170015], Table 6-3, Figure 6-6), since the SZ flow model is a single 
continuum model (Section 6.3.3). The recharge through each node of the UZ flow model is 
extracted and the corresponding recharge to the SZ site-scale flow model node was calculated 
(the UZ flow model grid is finer than the site-scale SZ grid). 
The distributed vertical recharge, limited to the northern-most portion of the SZ site-scale flow 
model area, was extracted from the Death Valley regional groundwater flow model (DAgnese et 
al. 1997 [DIRS 100131]). No recharge within the UZ flow model area was included from the 
regional flow model as this was accounted for separately (see above). A plot of distributed 
recharge from the regional-scale SZ flow model is provided by BSC (2004 [DIRS 170015], 
Figure 6-1). The details are considered in Recharge and Lateral Groundwater Flow Boundary 
Conditions for the Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 
[DIRS 170015]). 
Estimated recharge from all three sources is displayed in Recharge and Lateral Groundwater 
Flow Boundary Conditions for the Saturated Zone Site-Scale Flow and Transport Model (BSC 
2004 [DIRS 170015], Figure 6-8 and Section 6.2.4). 
Total recharge was about 1.54  106 m3/yr (1,250 acre-ft/yr). Of this total, about 
2.11  105 m3/yr (171 acre-ft/yr) was attributed to flux from the UZ flow model area and about 
9.47  104 m3/yr (76.8 acre-ft/yr) was attributed to infiltration along Fortymile Wash, leaving a 
remainder of about 1.24  106 m3/yr (1,000 acre-ft/yr) from distributed recharge. The recharge 
in each node of the regional model was extracted and the corresponding recharge in the site-scale 
model node was calculated (the regional model grid has a resolution of 1,500 m which is coarser 
than the site-scale model grid resolution). 
Groundwater inflows approximately along the eastern, northern, and western boundaries of the 
SZ site-scale flow model total 17.7  106 m3/yr (14,400 acre-ft/yr), 6.18  106 m3/yr 
(5,000 acre-ft/yr), and 3.75  106 m3/yr (3,040 acre-ft/yr), respectively (BSC 2004 
[DIRS 170015], pp. 6-27 to 6-29). These inflows, totaling 27.75  106 m3/yr (22,500 acre-ft/yr), 
represent nearly 18 times the estimated recharge from the surface in the model area. Of the total 
inflow for the eastern boundary, 17.5  106 m3/yr (14,200 acre-ft/yr), or 99 percent, occurs in the 
southern sector, nearest the Amargosa Desert (BSC 2004 [170015]), and nearly all of that occurs 
in layers 2 and 3 of the regional-scale flow model (BSC 2004 [DIRS 170015], Table 6-6) and 
represents flows in the lower carbonate aquifer (DAgnese et al. 1997 [DIRS 100131], p. 90, 
Figures 46 and 47). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-19 November 2004 
6.3.2.8 Discharge 
At the present time, there is no measurable natural discharge (i.e., springs or evapotranspiration 
within the SZ site-scale flow model domain); therefore, natural discharge to the surface is not 
represented in the SZ SS Flow Model. 
6.3.2.9 Heterogeneity 
Physical and chemical heterogeneity of the rocks and water in the SZ can affect groundwater 
flow and the transport of contaminants in the SZ. The principal forms of heterogeneity in the SZ 
site-scale model area are physical and may be primary (i.e., related to the formation of the rocks) 
or secondary (i.e., related to events subsequent to their formation). 
The most obvious form of primary heterogeneity is the mode of origin (i.e., volcanic rocks, 
clastic rocks, carbonate rocks, and alluvial deposits), which is the primary basis for subdividing 
the rocks into hydrogeologic units. Within each major category, further subdivisions are 
possible. Probably the major form of primary heterogeneity affecting groundwater flow in the 
SZ site-scale model area results from the origin of the volcanic rocks (i.e., ash flow or air fall 
pyroclastic deposits, lava flows, and volcanic breccias). The pyroclastic rocks (termed tuffs) 
primarily are nonwelded to densely welded, vitric to devitrified ash flow deposits separated by 
nonwelded vitric air fall deposits. Thus, the primary heterogeneity in physical character relates 
to whether the deposits resulted from massive eruptions of hot volcanic ash from volcanic 
centers that moved downslope as flows of fragmental material, or whether they resulted from 
explosive eruptions that injected volcanic fragments into the air to fall out as bedded ash fall 
tuffs. 
The thicker flow deposits, up to several hundred meters thick, were very hot, resulting in welding 
of the fragments into a dense mass. Thinner flows retained heat less effectively, resulting in 
partly welded to nonwelded ash flow tuffs. Ash fall tuffs, generally less than tens of meters 
thick, are cooled in the atmosphere and characteristically glassy (vitric) (Luckey et al. 1996 
[DIRS 100465], p. 17). 
The mode of origin controls the porosity and permeability of the volcanic rocks. The densely 
welded tuffs generally have minimal primary porosity and water-storage capacity but commonly 
are highly fractured and function as aquifers (Luckey et al. 1996 [DIRS 100465], p. 17). 
Nonwelded ash flow tuffs, when unaltered, have moderate to low matrix permeability but high 
porosity, and commonly constitute confining units. Ash fall tufts have high primary porosity and 
moderate to low permeability, and they generally function as confining units. 
As the tuff deposits cooled, they were subjected to secondary processes, including formation of 
cooling fractures, recrystallization or devitrification, and alteration of the initial glassy fragments 
to zeolite minerals and clay minerals, all of which affect the hydrologic properties of the rocks. 
Beginning with deposition and throughout their subsequent history, the rocks have been 
subjected to tectonic forces resulting in further fracturing and faulting. They also have been 
subject to changes in the position of the water table, which greatly affects the degree of alteration 
of the initially glassy deposits. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-20 November 2004 
The forms of secondary heterogeneity most affecting the SZ are fracturing, faulting, and 
alteration of glassy materials to zeolites and clay minerals. Fractures, where interconnected, 
transmit water readily, which accounts for the permeable character of the welded tuffs. Cooling 
fractures, which are pervasive in welded tuffs, tend to be strata-bound that is, confined to the 
welded portions of flows, whereas tectonic fractures tend to cut through stratigraphic units, as do 
faults. 
Nonwelded deposits are less subject to fracturing and more subject to alteration of the initial 
glassy deposits to zeolites and clay minerals, both of which reduce permeability. The presence 
of perched-water bodies in the UZ is attributed to the ubiquitous presence of a smectite-zeolite 
interval at the base of the Topopah Spring tuff, which, in the absence of through-going fractures, 
essentially stops the vertical movement of water (Luckey et al. 1996 [DIRS 100465], p. 46). 
The heterogeneity in permeability of different types of deposits led to the subdivision of the 
Yucca Mountain geologic section into five basic SZ hydrologic units: upper volcanic aquifer, 
upper volcanic confining unit, lower volcanic aquifer, lower volcanic confining unit, and lower 
carbonate aquifer. To accommodate the more extensive area of the SZ flow model, the HFM-19 
(BSC 2004 [DIRS 170008], Table 6-3) includes several additional units above and below these 
basic five units. Near Yucca Mountain, volcanic deposits generally form laterally extensive 
stratigraphic units; however, due to physical heterogeneity, porosity and permeability are highly 
variable both laterally and vertically. 
In the southern part of the SZ site-scale flow model domain, the volcanic deposits thin and 
inter-finger with valley fill deposits. The latter are heterogeneous (sand and gravel) because of 
their mode of deposition (Walker and Eakin 1963 [DIRS 103022], p. 14), but are not subject to 
the fracturing, faulting, and alteration types of heterogeneity that affect the volcanic rocks. 
Within the SZ site-scale model area, little specific information is available on the lower 
carbonate aquifer. However, information from nearby areas (DAgnese et al. 1997 
[DIRS 100131], p. 90, Figures 46 and 47) suggests that the lower carbonate aquifer is highly and 
uniformly permeable, and that the high permeability is attributed to pervasive solution enlarged 
fractures. 
Heterogeneity in material properties is a common characteristic of hydrogeologic units through 
which groundwater flows at the Yucca Mountain site. The heterogeneity exists at many different 
scales ranging from the pore scale to the regional scale. The larger scale heterogeneity, at scales 
of kilometers to 10s of kilometers, is effectively addressed via the different units within the HFM 
(BSC 2004 [DIRS 170008]) and incorporation of specific hydrogeologic features (e.g., faults and 
structural zones), and anisotropy. The pore scale heterogeneities are averaged via the concept of 
macroscopic parameters defined on the basis of a representative elementary volume (Freeze and 
Cherry 1979 [DIRS 101173], pp. 69 to 70). The governing equations used to model the 
groundwater flow use parameters defined on the basis of the representative elementary volume. 
For predominantly porous units such as bedded tuffs and alluvium, the size of the representative 
elementary volume may be on the order of a few cubic centimeters (De Marsily 1986 
[DIRS 100439], p. 15). For fractured rocks (volcanics and carbonates), the size of the 
representative elementary volume is less well defined but is accepted to be related to the density 
of fracturing and is generally much larger than for granular material (Freeze and Cherry 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-21 November 2004 
[DIRS 101173], p. 73). The 500-m grid spacing used for the flow model is sufficiently large to 
allow the use of representative elementary volume defined parameters for groundwater flow. In 
fact, the grid spacing is large enough that sub-grid scale heterogeneity needs to be considered 
with regard to radionuclide transport. This sub-grid heterogeneity has been shown to lead to an 
enhancement of dispersion with increasing scales of transport (De Marsily 1986 [DIRS 100439], 
pp. 247 to 248). Additionally, the uncertainty in the density of fracturing at the sub-grid scale 
leads to uncertainty in the groundwater velocity and the process of matrix diffusion. The 
groundwater modeling accounts for sub-grid heterogeneity by defining scaled dispersivities and 
flowing interval spacing (BSC 2004 [DIRS 170014]) in the transport abstraction modeling (BSC 
2004 [DIRS 170042], Section 6.5.2) as random variables characterized by probability density 
functions. 
The heterogeneity at intermediate scales between the grid size of 500 m and the large-scale 
features of the HFM are addressed using uncertainty in the anisotropy of hydraulic conductivity. 
A primary concern related to intermediate scale heterogeneity is the possibility of a fast pathway 
along a relatively continuous path. In the fractured volcanic aquifers beneath Yucca Mountain, 
the fast path, if it exists, is likely to be related to a fracture or structural feature. The hydraulic 
testing at the C-well complex (BSC 2004 [DIRS 170010], Section 6.2) demonstrated that at a 
large scale (about 1 km2) the hydraulic conductivity can be characterized as homogeneous, but 
anisotropic. The direction of anisotropy is likely related to the dominant direction of fractures 
and faulting. The impact of possible fast paths at an intermediate scale of heterogeneity is 
included in the transport simulations via the probability distributions of specific discharge, 
horizontal anisotropy in permeability, and flowing interval spacing (BSC 2004 [DIRS 170042], 
Section 6.5.2). The aggregate uncertainty in these and other parameters related to radionuclide 
transport result in simulated SZ transport times for nonsorbing species of less than 100 years in 
some Monte Carlo realizations of the SZ system (BSC 2004 [DIRS 170042], Figure 6-28). 
As noted previously, the properties of each hydrogeologic unit is taken as uniform, but uncertain, 
with the value being established during the calibration process. The model is still complex 
because of the lateral distribution of the hydrogeologic units. Heterogeneity of material 
properties at a variety of scales is still included in the model via several different mechanisms. 
First, large-scale heterogeneity is defined by the distribution of units in the HFM and the discrete 
hydrogeologic features incorporated in the SZ site-scale flow model. Sub-grid heterogeneity is 
included in the transport simulations through the probability distributions for flowing interval 
spacing and dispersivities. Finally, intermediate scale heterogeneity, which is most likely to be 
reflected in possible fast paths at scales up to several kilometers, is included as uncertainty in 
anisotropy. The uncertainty in the HFM is discussed in Section 6.4.6, where the different 
alternative models developed using different HFM are considered and compared. 
6.3.2.10 Role of Faults 
Faults and fault zones are hydrogeologic features that require special treatment in the SZ 
site-scale flow and transport models. Faulting and fracturing are pervasive at Yucca Mountain, 
and they greatly affect groundwater flow patterns because they may act as preferred conduits or 
barriers to groundwater flow. The role that faults play in facilitating or inhibiting groundwater 
flow depends on the nature of the fault (i.e., whether the faults are in tension, compression, or 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-22 November 2004 
shear) and other factors such as the juxtaposition of varying geologic units along the fault plane, 
the rock types involved, fault zone materials, and depth below land surface. 
Faunt (1997 [DIRS 100146]) investigated the effect of faulting on groundwater movement in the 
Death Valley region and developed a map of fault traces (Faunt 1997, [DIRS 100146] Figure 10) 
and developed diagrams (Faunt 1997 [DIRS 100146], Figure 11) showing the orientation of 
faults within the principal structural provinces of region. Faunt (1997 [DIRS 100146], p. 38) 
grouped the faults into three categories depending on their orientations relative to the present-day 
stress field (i.e., those in relative tension, compression, or shear). 
Faults in relative tension are more likely to be preferential conduits for groundwater, and faults 
in shear or compression are more likely to deflect or block groundwater movements. Within the 
SZ site-scale flow model area, faults modeled to have the most evident effects on groundwater 
movement, such as effects on potentiometric contours, include the Solitario Canyon, U.S. 
Highway 95, Crater Flat, and Bare Mountain faults (Figure 6-3), all of which appear to act as 
barriers to groundwater flow. Faults within the SZ site-scale model area of hydrologic 
importance include the Spotted Range-Mine Mountain shear zone (Figure 6-37), which Faunt 
(1997 [DIRS 100146], p. 34) describes as a major high-permeability zone in the lower carbonate 
aquifer. The following features are given special treatment is accorded in the SZ site-scale flow 
model: Crater Flat fault, Solitario Canyon fault, U.S. Highway 95 fault, Bare Mountain fault, 
Imbricate fault zone (between the Ghost Dance and Paintbrush Canyon faults at Yucca 
Mountain), Fortymile Wash zone (which may not be a fault), and the east-west barrier (which is 
shown on Figure 6-37 and appears to cause the large hydraulic gradient north of Yucca 
Mountain). These features fall into three categories depending on their hydrologic impacts: 
(1) zones of permeability enhancement parallel to faults and zones of permeability reduction 
perpendicular to faults (Crater Flat and Solitario Canyon faults), (2) zones of permeability 
enhancement (Bare Mountain fault, Imbricate fault zone, Fortymile Wash zones, and Spotted 
Range-Mine Mountain zone) (Figure 3-37), and (3) zones of uncertain behavior (U.S. Highway 
95 fault). 
6.3.3 Groundwater Flow Processes 
Modeling simplifications used in modeling the groundwater flow process include those of the 
regional scale models and the SZ site-scale flow models, and those made in estimating 
parameters that are used as input to these models. For the following reasons, the effective 
continuum representation of fracture permeability is used. 
 On the scale represented by the SZ site-scale flow model, the site is well represented by 
a continuum flow model. Aquifer hydraulic tests show evidence of fracture flow near 
Yucca Mountain (Geldon et al. 1997 [DIRS 100397]). Numerical modeling of fracture 
properties is done in one of three ways: discrete fracture models, effective continuum 
models, or dual-continuum models. Dual-continuum models are not needed because 
transient simulations are not performed. For steady-state SZ flow calculations, 
dual-continuum formulations are equivalent to single-continuum formulations. Discrete 
fracture models represent each fracture as a distinct object within the modeling domain. 
Although a discrete fracture model might reproduce the flow system more accurately, 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-23 November 2004 
flow modeling is adequately conducted using a continuum model for the following 
reasons: 
- At Yucca Mountain, studies of the density and spacing of flowing intervals generally 
indicate that flow occurs through fracture zones (BSC 2004 [DIRS 170014], 
Figure 6-2). The fractures or fracture zones are located in various geological units, 
and in most cases, no single zone dominates the flow through a well. Geochemical 
studies (see Figure A6-62) independently confirm a south-southeasterly trace of the 
particle flow path. For the limited set of wells (Luckey et al. 1996 [DIRS 100465], 
Figure 11), flow appears to be carried through fracture zones separated by a few tens 
of meters rather than by a few individual fractures. 
- Part of the flow system is an alluvium unit for which flow and transport is 
appropriately modeled using a continuum model. 
- The drawdown response to pumping at wells surrounding the C-wells complex in 
multiwell pump tests indicates a well-connected fracture network in the Miocene 
tuffaceous rocks in this area (Geldon et al. 1998 [DIRS 129721], p. 31). 
The following assumptions also apply to the continuum modeling approach used in the SZ 
site-scale flow model for supporting the TSPA-LA. 
 Estimates of discharge from the volcanic aquifer, elicited from the SZ expert elicitation 
panel, are applicable to the entire flow path from the repository to the accessible 
environment. The estimates of specific discharge from the SZ expert elicitation 
(CRWMS M&O 1998 [DIRS 100353], p. 3-8) primarily were based on data from 
hydraulic testing in wells in volcanic units and the hydraulic gradient inferred from 
waterlevel measurements. The relative values of groundwater flux in the volcanic 
aquifer and along the flow path farther to the south are constrained by the calibration of 
the SZ site-scale flow model; that is, the limits of permeability values of important 
hydrological units that allow reasonable calibration are used to set limits on specific 
discharge. It is reasonable to extrapolate the degree of uncertainty in the absolute value 
of groundwater flux from the volcanic aquifer to the flow path farther to the south. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-24 November 2004 
 Horizontal anisotropy in permeability is adequately represented by a permeability tensor 
that is oriented in the north-south and east-west directions. In support of the TSPA-LA, 
horizontal isotropy and anisotropy are considered for radionuclide transport in the SZ 
(BSC 2004 [DIRS 170010]). The numerical grid of the SZ site-scale flow model is 
aligned north-south and eastwest, and values of permeability may be specified only in 
directions parallel to the grid. Analysis of the probable direction of horizontal 
anisotropy shows that the direction of maximum transmissivity is N 33 E (Winterle and 
La Femina 1999 [DIRS 129796], p. iii), indicating that the anisotropy applied on the SZ 
site-scale model grid is within approximately 30 of the inferred anisotropy. Horizontal 
isotropy was assumed in the calibrated flow model, but sensitivity analyses were 
performed to assess the impact of uncertainty in the anisotropy and presented in 
Saturated Zone Flow and Transport Model Abstraction (BSC 2004 [DIRS 170042], 
Section 6.5.2). 
 Horizontal anisotropy in permeability applies to the fractured and faulted volcanic units 
of the SZ system along the groundwater flow paths that run from the repository to points 
south and east of Yucca Mountain. The inferred flow path from beneath the repository 
extends to the south and east. This is the area in which potential anisotropy could have 
an important impact on radionuclide transport in the SZ. Given the conceptual basis for 
the anisotropy model, it is appropriate to apply anisotropy only to those hydrogeologic 
units that are dominated by groundwater flow in fractures. The more detailed discussion 
of anisotropy is provided in Section 6.4.3. 
 Anisotropy in permeability represents an alternative conceptual model of groundwater 
flow at the Yucca Mountain site. Sufficient uncertainty in the analysis of horizontal 
anisotropy exists to warrant consideration of two possible conceptual models: one with 
anisotropy and one without anisotropy (i.e., isotropic permeability). 
 Changes in the water-table elevation (due to future climate changes) will have negligible 
effect on the direction of the groundwater flow near Yucca Mountain although the 
magnitude of the groundwater flux will change. This supposition has been studied in 
regional-scale (DAgnese et al. 1999 [DIRS 120425]) and subregional-scale (Czarnecki 
1984 [DIRS 101043]) flow models. These studies found that the flow direction did not 
change significantly under increased recharge scenarios. The studies were based on 
two-dimensional confined aquifer models that did not take into account the free surface 
boundary at the water table or the saturation of geological units that currently are in the 
UZ overlying the present-day SZ. These UZ tuffs generally have a lower permeability 
than those in the SZ, and as such, UZ units are not likely to introduce faster fluxes 
(BSC 2004 [DIRS 169861] Appendix A). 
 Future water supply wells that might be drilled near Yucca Mountain (including outside 
the regulatory boundary) will have a negligible effect on the hydraulic gradient. Water 
levels at the southern boundary of the SZ site-scale flow and transport models (in the 
Amargosa Valley) currently reflect the effect of well pumpage (Luckey et al. 1996 
[DIRS 100465], p. 41). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-25 November 2004 
 In the analysis presented in this report, temperature is modeled to be approximately 
proportional to the depth below the ground surface. Modeling a uniform temperature 
gradient with depth is equivalent to a model of uniform geothermal heat flux through a 
medium of homogeneous thermal conductivity. In addition, the temperature at the 
ground surface is modeled to be equal to a uniform value. The data on temperature in 
boreholes presented in Sass et al. (1988 [DIRS 100644], Figures 4 to 8, Figure 10) 
indicate that there is significant variability in the temperature gradient at different 
locations and within individual wells, presumably due to advective redistribution of heat 
from infiltration and vertical groundwater flow. However, these data also indicate that 
the temperature gradients generally become more linear with increasing depth below the 
water table. It is important to note that the goal of assigning temperature variations with 
depth in the SZ site-scale flow model is to account for resulting variations in fluid 
viscosity at different depths in the SZ. The viscosity of water changes by a factor of 
only about 3.3 over the temperature range of 20.C to 100.C (Streeter and Wylie 1979 
[DIRS 145287], p. 536) that is expected within the range of depths in the SZ site-scale 
model domain. Thus, the linear approximation of the temperature gradient is adequate 
to capture the general effects of variations in groundwater viscosity with depth in the SZ 
site-scale flow model. The density also varies with temperature, but the effect is much 
smaller than viscosity. Over the temperature range of 20.C to 100.C, water density 
varies only a few percent. Using a variable viscosity allows the calibration of intrinsic 
permeability to be made instead of hydraulic conductivity. The former is a rock 
property, whereas the latter is a rock and fluid property. This approach, in turn, allows 
for more accurate flux calculations on the boundaries of the model. 
 The confined-aquifer solution approach is used in the SZ site-scale flow model. The 
approach treats the upper boundary as if there is no UZ and, therefore, solves a 
simplified and computationally more efficient numerical model. In the numerical 
model, the top surface has boundary conditions of applied recharge flux. The confined 
aquifer solution was enforced in the FEHM code by adding a large artificial head to the 
numerical solution. This artificial head was later subtracted after the computer run to 
recover the true solution. Because none of the fluid or rock properties depend on head, 
no changes to the true solution occur other than forcing the bookkeeping coding in 
FEHM to model the system as fully saturated conditions. If this procedure were not 
adopted, small variations in head around the waterlevel value would result in FEHM 
testing for an air phase, thus decreasing the efficiency. The negative side of this 
approach is that the top surface of the numerical model corresponds to the measured 
water-table surface and may be inconsistent with the model-derived water table surface. 
This discrepancy affects the flux through the model domain. The error is generally 
small because the flowing area is proportional to the thickness of the model in the 
north-south direction, and the weighted root mean square residual between the calibrated 
and measured heads is 16 m (see Section 6.1.2), compared to a model thickness of 
approximately 3,000 m. Furthermore, the discrepancy can be checked after the model is 
run. The numerical model weighted root mean square residual was about 16 m for the 
more than 100 head observations. Assuming that the water table solution is in error by 
this amount, error for the flow area for the horizontal head gradient is small. Care was 
taken in the calibration process to model the low head gradient area to the south and east 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-26 November 2004 
of Yucca Mountain accurately. Specified head boundary conditions on the lateral 
boundaries were set with no vertical gradient. It should be noted that the model allows 
for vertical flows that arise from recharge and heterogeneity. The numerical approach 
used is similar to the classical Dupuit-Forcheimer method. 
6.4 CONSIDERATION OF ALTERNATIVE CONCEPTUAL MODELS 
The SZ site-scale flow model is used in the performance assessment calculations to evaluate the 
potential risks to groundwater users downgradient from the repository area. The results of these 
performance assessment calculations depend strongly on the specific discharge of groundwater 
leaving the repository area, as well as on the flow paths and the distribution of flow among the 
various hydrostratigraphic units that carry, deflect, or otherwise affect the flow. The alternative 
conceptual models (ACMs) presented here were investigated because they represented a 
well-publicized hydrologic concern such as large hydraulic gradient (LHG) or were related to a 
model feature (anisotropy or fault), or conceptualization (potentiometric surface), that had a 
possibility of strongly affecting the specific discharge calculations. Thus, it is important to 
understand how ACMs and their representations may affect the specific discharge and flow 
paths. This section presents analyses of the ACMs, their representation in the numerical model, 
and a discussion about possible impacts on the model outputs (specific discharge and flow 
paths). ACMs affecting model outputs are discussed in Section 6.7, and their associated 
uncertainty is propagated to the stochastic generation of radionuclide breakthrough curves in the 
TSPA calculations. 
The SZ site-scale flow model described in detail in Section 6.5 also provides the basis for the 
ACMs discussed here. That is, the same numerical grid and HFM conceptual model were used 
throughout this section. Various parameterization schemes were used to define the ACMs. For 
example, the LHG HFM conceptual model used a different feature set (without the east-west 
barrier) from the SZ site-scale flow model. Otherwise, the models are the same. The following 
ACMs were evaluated: 
 Large Hydraulic Gradient: This ACM deals with the presence and absence of the LHG. 
 Solitario Canyon Fault: This ACM deals with the vertical extent of Solitario Canyon 
fault. 
 Anisotropy: This ACM deals with anisotropy in permeability. 
 Potentiometric Surface (Horizontal Hydraulic Gradient) and WaterLevel Data: This 
ACM deals with different interpretations of water level elevation and water level 
contouring alternatives. 
 Water Table Rise: This ACM deals with future water table rise. 
 Alternate SZ Site-scale Flow Model (HFM Reinterpretation, HFM-27 and Additional 
Data): This ACM deals with the impact of data acquired and analyses performed since 
the development of the SZ site-scale flow model on radionuclide transport predictions in 
the SZ. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-27 November 2004 
6.4.1 Large Hydraulic Gradient 
It is important to understand how the presence or absence of the LHG and its representation in 
the numerical model affect estimates of groundwater specific discharge and flow paths. Absence 
of the LHG means that the high heads and/or high gradients are an artifact of interpreting water 
levels as the regional water table when they are representing a perched water body. In the 
alternative conceptual models of the LHG that follow, the absence of the LHG are implicitly 
accounted for by assigning a low weight (relative to other observations) in the numerical 
calibrations to those wells that are suspected of being perched. 
The LHG north of Yucca Mountain is a feature of the flow system near Yucca Mountain that has 
been the subject of interest over the years (Figures 6-2 and 6-4). Compared to the very gentle 
gradient from the repository to points south, the gradient north of the site is much larger. 
Potential causes of this gradient are discussed in Section 6.3.2.4. To model the LHG, a 
low-permeability east-west feature has been incorporated into the base case conceptual model of 
SZ flow north of Yucca Mountain. Because there is little field evidence for the presence of this 
feature, alternative conceptualizations are plausible. The Claim Canyon Caldera, north of Yucca 
Mountain, is an area of extensive hydrothermal alteration, which may result in a generalized 
reduction in permeability in the hydrogeologic units in this area. Permeability changes in similar 
environments have been studied by economic geologists (Norton and Knapp 1977 
[DIRS 147379]). 
Because the LHG occurs north of Yucca Mountain, the change in the models simulated 
potentiometric surface due to the LHG conceptualization is minimal if the downstream gradients 
of Yucca Mountain are modeled accurately. The different model-generated potentiometric 
surfaces, though similar, lead to considerable differences in flow paths for fluid particles leaving 
the repository as well as large differences in flow directions for groundwater entering the 
repository area. These different conceptualizations are important to the overall understanding of 
the flow system, and, thus, a detailed evaluation of the ACMs is warranted. 
The SZ site-scale flow model has been used to evaluate three different conceptual models of the 
LHG. In addition to the original conceptualization described above, a second conceptual model 
was evaluated that models the apparent LHG to be a result of low-permeability, hydrothermally 
altered rock north of Yucca Mountain. A third conceptual model of the LHG was evaluated that 
takes into account not only the area of hydrothermally altered rock north of Yucca Mountain but 
also the observed faults in the northwestsoutheast trending washes in northern Yucca Mountain. 
These models are referred to as the altered, no fault (ANF) and altered, with fault (AWF) 
models, respectively. The feature sets for the alternative conceptual models of the LHG are 
shown in Figures 6-5 and 6-6 (see a more detailed discussion of these feature sets in 
Section 6.5.3.4). Regardless of their conductivity, these faults tend to divert water along their 
strike and have the potential for segregating flow regimes near Yucca Mountain. Section 6.7.1.3 
shows that the flow paths generated with the LHG ACMs are consistent with the SZ site-scale 
flow model. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-28 November 2004 
Source: Zyvoloski et al. 2003 (DIRS 163341), Figure 2b. 
UTM = Universal Transverse Mercator. 
Figure 6-5. Features of the SZ Site-Scale Flow Model with EastWest Barrier Included 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-29 November 2004 
Source: Zyvoloski et al. 2003 (DIRS 163341), Figure 2c. 
UTM = Universal Transverse Mercator. 
Figure 6-6. Features of the LHG-ACM SZ Site-Scale Flow Model Without the EastWest Barrier 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-30 November 2004 
6.4.2 Solitario Canyon Fault 
The Solitario Canyon fault separates Crater Flat from Yucca Mountain (Figure 6-2). The 
representation of the Solitario Canyon fault is an important part of the SZ site-scale flow model 
because it potentially can control flow from Crater Flat to Fortymile Wash in the area of the 
repository. The impact on the model of these features is to generate a higher hydraulic gradient 
to the west of Yucca Mountain and to impede flow from Crater Flat to Yucca Mountain. This in 
turn affects the eastern extent of travel of fluid leaving the repository area. Thus, the conceptual 
model of the Solitario Canyon fault influences the path length in the alluvial material of 
groundwater that originated from beneath the repository region. 
While the Solitario Canyon fault has been identified as a major fault in the SZ site-scale flow 
model region, conceptual uncertainty remains in the HFM-27 as to the depth of this fault (Potter 
et al. 2002 [DIRS 160060]). This uncertainty translates into uncertainty regarding the likely 
hydraulic behavior of this feature at depth. The SZ site-scale flow model includes the Solitario 
Canyon fault as a discrete feature that extends from the bottom of the model to the top of the 
water table. The fault is modeled as an anisotropic feature with greater permeability along the 
plane of the fault than across it. It is possible that this treatment of the anisotropy is 
inappropriate where it cuts the carbonate aquifer deep in the model domain. To investigate the 
importance of the Solitario Canyon fault depth, an alternative conceptualization has been 
simulated in which the fault extends from the water table only to the top of the carbonate aquifer. 
6.4.3 Anisotropy 
Anisotropy occurs when hydraulic properties have different values in the three different 
directions: vertical, horizontal along the direction of maximum permeability, and horizontal 
along the direction of minimum permeability. This ratio of horizontal to vertical permeability is 
in the general accepted range as given by the expert elicitation panel (CRWMS M&O 1998 
[DIRS 100353], Table 3-2). 
6.4.3.1 Vertical Anisotropy 
A fractured or porous media exhibits anisotropy when hydraulic properties are not uniform in all 
directions. For Yucca Mountain, anisotropic permeability potentially affects the specific 
discharge, the flow paths, and the flow path lengths in the volcanic tuffs and alluvium. The SZ 
site-scale flow model includes a horizontal to vertical anisotropy ratio of 10:1, a typical value, in 
many of the units. For the SZ site-scale flow model, anisotropy ratios generally were kept 
constant during the analysis of the groundwater flow regime. Some units were modeled with 
isotropic permeability. These units were the granite confining, the clastic units, the upper 
volcanic confining unit, the lava-flow aquifer, and the limestone aquifer. Faults and features 
were generally modeled with anisotropic permeability, though not with the same horizontal to 
vertical ratio as the hydrogeologic units. Conceptual models both with and without vertical 
anisotropy are considered. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-31 November 2004 
6.4.3.2 Horizontal Anisotropy 
The faults in the SZ site-scale flow model include both vertically and horizontally anisotropic 
features that have high conductivity in the strike and vertical directions and low conductivity in 
the direction across the fault. In general, the x direction permeability of major faults was 
calibration parameter. However, the anisotropy ratios were kept constant during the calibration 
process. In addition, the predominant northsouth trending faults near Yucca Mountain were 
investigated using an ACM with variable horizontal anisotropy ratios (northsouth to eastwest 
permeability change). 
The predominately northsouth trending faults near Yucca Mountain were investigated using an 
ACM with variable horizontal anisotropy ratios (northsouth to eastwest permeability changes). 
The area to which the anisotropy ratio was applied is bounded by a quadrilateral shown in 
Figure 6-7. This effect was investigated by re-running the SZ calibrated model with a 
5:1 permeability ratio and checking the sensitivity of the calibration. A detailed description of 
the development of the horizontal anisotropy distribution used in this model is found in 
Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010], Section 6.2.6). The TSPA 
calculations generated flow fields with that distribution, illustrated in Figure 6.2-3 of the in situ 
testing report (BSC 2004 [DIRS 170010], Section 6.2.6). Incorporating the 5:1 permeability 
anisotropy in the area of the north-south trending faults at Yucca Mountain into the calibrated 
model resulted in predicted hydraulic heads that were slightly closer to the observed heads than 
for the model calibration without anisotropy. The differences in predicted heads and their 
impacts on the specific discharge, the flow-path direction, and flow-path lengths in volcanic tuffs 
and alluvium were within the uncertainty ranges used in the TSPA (BSC 2004 [DIRS 170042], 
Sections 6.4 and 6.5.2.10). Because horizontal anisotropy impacts model results, this parameter 
has been included in the TSPA analysis and, thus, is fully accounted for in terms of effect on 
repository performance. 
6.4.4 Potentiometric Surface (Horizontal Hydraulic Gradient) and WaterLevel Data 
Waterlevel data are important parameters for model development. Measured water levels were 
used directly as calibration targets in this model report and to construct potentiometric surfaces 
used to derive horizontal and vertical hydraulic gradients (BSC 2004 [DIRS 170009]). 
Additionally, waterlevel responses to pumping were used to estimate a distribution of 
horizontal anisotropies for certain model zones (BSC 2004 [DIRS 170010], Section 6.2). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-32 November 2004 
Output DTN: LA0304TM831231.002. 
UTM = Universal Transverse Mercator. 
Figure 6-7. Horizontal Anisotropy Is Applied to the Blue Crosshatched Area 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-33 November 2004 
The purpose of this section is to compare four versions of the potentiometric surface of the 
uppermost part of the SZ for the SZ site-scale flow and transport model domain. There are 
differences in the potentiometric surface represented in each of these versions because of 
differences in purpose, assumptions, conceptual models, and methods by which the surfaces 
were constructed. Three potentiometric surfaces were derived from the following four sources: 
1. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport 
Model (USGS 2001 [DIRS 154625], Section 6.2) 
2. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport 
Model (USGS 2001 [DIRS 157611], Section 6.2) 
3. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170009], Section 6.4) 
4. Development of Numerical Grids for UZ Flow and Transport Modeling (BSC 2004 
[DIRS 169855], Section 6.2). 
These are not the only versions of the potentiometric surface produced for this area; however, 
model comparisons will be limited to Sources 1, 3, and 4, all of which have been developed since 
the year 2000. Items 1 and 2 are summarized in the revised report, Water-Level Data Analysis 
for the Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170009]). 
Item 2, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(USGS 2001 [DIRS 157611]), is not compared because all of its features are also included in 
Item 3. 
The SZ site-scale flow model calibration described in this report used a relatively low weighting 
for observations in the high-head, LHG area because of the uncertainty associated with those 
observations. Some of these uncertainties are due to the waterlevel data in wells USW G-2 and 
UE-25 WT-24. 
6.4.4.1 WaterLevel Data Analysis for the SZ Site-Scale Flow Model (Base Case Model) 
A potentiometric surface map (Figure 6-4) was presented in Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport Model (USGS 2001 [DIRS 154625], Figures 1-1 
and 1-2). The purpose of the analysis documented in this USGS report was to provide the SZ 
site-scale flow model with the configuration of the potentiometric surface and target waterlevel 
data for model calibration. This analysis was used to support the site recommendation. The 
source data consisted of waterlevel data from boreholes within the SZ site-scale flow model 
domain and from one borehole (UE-25 J-11) adjacent to the SZ site scale flow model domain. 
The SZ site-scale flow model domain coordinates range from Universal Transverse Mercator 
Easting of 533,340 meters to 563,340 meters and from Universal Transverse Mercator Northing 
of 4,046,782 meters to 4,091,782 meters (Zone 11, North American Datum 1927) (BSC 2004 
[DIRS 170009], Figure 1-2). 
Water levels were used from a number of wells in the northern part of the domain that defined a 
region of the LHG. An important assumption for this analysis was that, while the wells defining 
the LHG were suspected to represent perched water (USW G-2, UE-25 WT-24), there were 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-34 November 2004 
insufficient data to exclude these water levels from the analysis. The output of this analysis 
(DTN: GS000508312332.001 [DIRS 149947]) was used to construct the potentiometric surface 
using gridding software. 
6.4.4.2 Updated WaterLevel Data Analysis for the SZ Site-Scale Flow Model 
An updated potentiometric surface map was presented in Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170009], Section 6). 
The purpose of the analysis documented in BSC (2004 [DIRS 17009]) was to provide the SZ 
site-scale flow model with an updated configuration of the potentiometric surface. The updated 
waterlevel data included water levels obtained from the NC-EWDP and data from borehole 
USW WT-24. Source data included data used for the USGS waterlevel data analysis described 
in Section 6.4.4.1 (USGS 2001 [DIRS 157611], Sections 6.2 and 7.2), and the potentiometric 
surface was constructed for the same domain. An ACM was considered in this revision by 
incorporating the following two assumptions: 
 Water levels in boreholes USW G-2 and UE-25 WT#6 in the northern part of Yucca 
Mountain and in borehole NC-EWDP-7S in southern Crater Flat represent perched 
conditions. 
 Water levels in USW WT-24, at approximately 840 m above sea level, represent the 
regional potentiometric level. 
The output of this analysis was a potentiometric surface map assuming perched conditions north 
of Yucca Mountain (DTN: GS010608312332.002 [DIRS 163555]). The method used to 
construct this potentiometric surface differed from that used for the map discussed in the 
preceding section (USGS 2001 [DIRS 154625]). Automatic gridding software was used for the 
original USGS waterlevel data analysis (USGS 2001 [DIRS 154625]), while contours for BSC 
(2004 [DIRS 170009], Section 6.4) were hand drawn by project hydrologists. 
The potentiometric surface maps developed in the waterlevel data analyses 
(USGS 2001 [DIRS 154625], Figure 1-1; BSC 2004 [DIRS 170009], Figure 6-1) are compared 
in Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170009]). Because the two maps were based on similar data, the general 
characteristics of the surfaces were similar. The most significant difference noted is the 
representation of the LHG area north of Yucca Mountain. Exclusion of waterlevel data from 
boreholes USW G-2 and UE-25 WT #6 considered to represent perched conditions reduced the 
LHG significantly. Another difference noted is that potentiometric contours in Water-Level 
Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 
[DIRS 170009]) are no longer offset where they cross faults. Offsets in the waterlevel map of 
USGS (2001 [DIRS 154625]) were noted in the waterlevel data analysis of BSC (2004 
[DIRS 170009]) and were described as unexpected where contours are perpendicular or nearly 
perpendicular to faults. The contour interval for this map (Figure 6-8) is variable. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-35 November 2004 
Source: DTN: GS000508312332.002 [DIRS 149947]; BSC 2004 [DIRS 170009], Figure 6-1. 
UTM = Universal Transverse Mercator. 
Figure 6-8. Contour Plot of WaterLevel Data for the SZ Flow and Transport Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-36 November 2004 
6.4.4.3 Flow Model Lower Boundary for the UZ Flow Model 
The development of numerical grids of the unsaturated hydrogeologic system beneath Yucca 
Mountain is described in Development of Numerical Grids for UZ Flow and Transport Modeling 
(BSC 2004 [DIRS 169855]). A representation of the potentiometric surface was an output of the 
UZ flow model report analysis report because this surface defined the lower UZ model boundary 
(Figure 6-10 Note: Figure 6-9 was deleted.]). The domain for this interpretation of the 
potentiometric surface is smaller than the SZ site-scale flow model domain encompassing 
approximately 40 km2 (BSC 2004 [DIRS 169855], Section 6.2) as compared to the 
approximately 1,350 km2 of the SZ site-scale flow model domain (USGS 2001 [DIRS 154625], 
Figures 1-1 and 1-2). 
The lower boundary for the UZ model was established using water levels consistent with the 
perched water interpretation of the waterlevel data analysis (BSC 2004 [DIRS 170009]). Two 
gridding steps were used to create a reference horizon file representing the lower boundary. This 
gridding process was noted in Development of Numerical Grids for UZ Flow and Transport 
Modeling (BSC 2004 [DIRS 169855], Sections 6.4.2 and 6.9.1) as producing small deviations in 
the resulting potentiometric surface with respect to the original digitized potentiometric surface. 
These deviations were considered to be relatively minor (i.e., less than 5 meters near the 
repository footprint). Larger differences of up to 60 meters between the output potentiometric 
surface and the potentiometric surface discussed in the report (BSC 2004 [DIRS 170009]) were 
attributed to errors associated with contour digitization before generation of the potentiometric 
surface (BSC 2004 [DIRS 169855], Sections 6.4.2 and 6.9.1). 
Because of the UZs smaller domain, comparison of the surface derived from the SZ site-scale 
flow model calibration to Development of Numerical Grids for UZ Flow and Transport 
Modeling (BSC 2004 [DIRS 169855]) is limited. Differences in potentiometric surfaces can be 
attributed to differences in purpose, assumptions, conceptual models, and methods by which the 
surfaces were constructed. The discussion of the different potentiometric surfaces is presented in 
BSC (2004 [DIRS 170009], Section 6.5). 
6.4.5 Water Table Rise 
6.4.5.1 Water Table Rise Beneath Repository 
In addition to modeling SZ Flow under current conditions, it is also necessary to consider 
conditions over the next 10,000 years, as the climate changes. A higher water table is expected 
in the Yucca Mountain region for future wetter climatic conditions. A rise in the water table 
could impact flow paths from beneath the repository in the SZ, but is handled in a simplified, 
conservative manner, as explained below. A higher water table has clear impacts on 
radionuclide transport in the UZ by shortening the transport distance between the repository and 
the water table. SZ modeling analyses considered in this report indicate that a rise in the water 
table will cause flow paths from beneath the repository to the accessible environment to be in 
units with lower permeabilities than the ones under the current water table conditions which will 
result in longer radionuclides transport time through the SZ. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-37 November 2004 
Source: BSC 2004 (DIRS 169855), Figure 6-2. 
NOTE: Figure 6-9 was deleted. Figures were not renumbered due to figure cross-referencing in other documents. 
NSP = Nevada State Plane Coordinate System. 
Figure 6-10. Plan-View Schematic Showing Boreholes, Contoured Water Table (Elevation in Meters), 
UZ Model Boundary, Repository Outline, ESF, and Enhanced Characterization of the 
Repository Block Cross-Drift 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-38 November 2004 
Several independent lines of evidence are available for estimating the magnitude of rise in the 
water table beneath the repository at Yucca Mountain under previous glacial-transition climatic 
conditions (Forester et al. 1999 [DIRS 109425], pp. 56 and 57. Mineralogic alteration 
(zeolitization and tridymite distribution) in the UZ at Yucca Mountain shows no evidence that 
the water table has risen more than 60 m (200 ft) above its present position in the geologic past 
(Levy 1991 [DIRS 100053], p. 477). Analyses of 87Sr/86Sr ratios in calcite veins of the UZ and 
SZ at Yucca Mountain indicated previous water table positions of 85 m (279 ft) higher than 
present (Marshall et al. 1993 [DIRS 101142], p. 1948). Recently completed wells at paleospring 
discharge locations near the southern end of Crater Flat revealed shallower-than-expected 
groundwater (Paces and Whelan 2001 [DIRS 154724]; BSC 2004 [DIRS 168473], Table I-1), 
with depths of only 17 to 30 m (56 to 100 ft) to the water table. These findings indicate that the 
water table rise during the Pleistocene at these paleospring locations could not have been more 
than about 30 m (100 feet) due to the development of discharge locations. The results of the 
mineralogical and geochemical studies showing maximum water table rise of up to 85 m 
reflected evolution of past climates of up to 1 million years, which included the effects of glacial 
climates. The maximum water table rise under monsoon and glacial-transition climates for the 
next 10,000 years is, therefore, expected to be smaller because the monsoon and 
glacial-transition climates are warmer and dryer than the glacial climate (Sharpe 2003 
[DIRS 161591]). 
Interpretation of the water levels in wells at the southern end of Crater Flat, in relation to water 
table rise, is complicated by several factors. The paleospring discharge locations at the southern 
end of Crater Flat are not along the flow path from Yucca Mountain. Also, a higher groundwater 
flow rate is expected under future wetter climatic conditions and the principles of hydrogeology 
indicate that a uniform rise in the water table is not expected to occur unless the higher water 
table leads to a corresponding increase in the transmissivity (due to increased saturated 
thickness). A higher groundwater flow rate implies a higher hydraulic gradient, a larger 
transmissivity, or both along any given flow line. Thus, the water table at upgradient locations 
would be expected to rise more than the water table at downgradient locations, resulting in a 
nonuniform rise in the water table across the flow system. 
Groundwater flow modeling of the response to a doubling of the mean annual precipitation 
indicated a maximum increase of 130 m (430 ft) of the water table in the vicinity of Yucca 
Mountain (Czarnecki 1985 [DIRS 160149]). This water table was overestimated because the 
analysis by Czarnecki (1985 [DIRS 160149]) was limited to two dimensions. In addition, 
average precipitation under monsoon and glacial-transition climates is less than twice the 
present-day value in the Yucca Mountain area, and the percolation flux resulting from the 
precipitation increase by Czarneck (1985 [DIRS 160149]) was also conservatively modeled. 
More recent groundwater flow modeling of the regional flow system under paleoclimate 
conditions simulated water levels of 60 to 150 m (200 to 490 ft) higher than present beneath 
Yucca Mountain (DAgnese et al. (1999 [DIRS 120425], p. 2). Coarse resolution of the 
numerical grid used by the DAgnese et al. (1999 [DIRS 120425]) flow modeling is believed to 
have resulted in an overestimate of water table rise (150 m). 
Alternatively, an approximate calculation illustrates how the increased groundwater flow rate 
inferred for glacial-transition climate conditions could result in a higher water table at Yucca 
Mountain. Consider a groundwater flow line from beneath Yucca Mountain to near the southern 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-39 November 2004 
boundary of the SZ site-scale flow model domain. Simulations of groundwater flow under past 
glacial-transition climate conditions in DAgnese et al. (1999 [DIRS 120425], Figure 13) show 
that groundwater discharge would be initiated at the toe of the Fortymile Wash system, near the 
southern boundary of the SZ site-scale flow model domain. The present water table elevation at 
this location is about 700 meters (2,300 feet), and the water table beneath Yucca Mountain is at 
about 730 meters (2,400 feet) elevation. The drop in hydraulic head along this groundwater flow 
line is about 30 meters (100 feet). It is estimated that the groundwater flux along this flow line 
would be greater by a factor of about 4 for glacial-transition climate conditions (BSC 2003 
[DIRS 170042], Table 6-5). Attributing increases in groundwater flux to increases in the 
hydraulic gradient only (i.e., no increase in transmissivity), the head drop along the flow path 
would have to increase from 30 meters (100 feet) to four times 30 meters, or 120 meters 
(400 feet). Furthermore, for groundwater discharge to be initiated near the southern end of the 
flow line, the water table would have to rise by about 30 meters (100 feet) at that location. 
Therefore, the water table elevation beneath Yucca Mountain would have to be 700 meters + 
30 meters + 120 meters (2,300 feet + 100 feet + 400 feet), or a value of 850 meters (2,800 feet) 
for glacial-transition climate conditions, based on this simplified calculation. A water table 
elevation of 850 meters (2,800 feet) beneath Yucca Mountain constitutes a rise of about 
120 meters (400 feet) relative to present conditions. 
For the TSPA-LA calculations, a conservative approach in which a rise in the water table of 
120 meters (400 feet) is imposed in the UZ transport model for monsoon and glacial-transition 
climatic conditions (BSC 2004 [DIRS 170041], Section 6.4.8). This effectively decreases the 
length of the flow path of radionuclides in the UZ by about 120 meters. The 120-meter 
(400-foot) rise in the water table due to climate change is a conservative estimate that minimizes 
the transport time in the UZ. In addition, the 120-meter (400-foot) rise in the water table is 
assumed to occur immediately following the change to wetter climatic conditions. In reality, 
there could be a significant period of adjustment in the SZ flow system in response to increased 
recharge related to climate change. 
Overall, the treatment of water table rise due to climate change in the TSPA-LA tends to 
underestimate the transport times of radionuclides through the natural system. However, given 
the differing estimates and lack of definitive information on the magnitude and timing of 
water table rise, it constitutes a reasonable bounding approximation. 
6.4.5.2 Incorporation of Water Table Rise into the SZ Flow and Transport Models 
The effects of climate change on radionuclide transport simulations in the SZ are incorporated 
into the TSPA analyses by scaling the simulated SZ breakthrough curves by a factor 
representative of the alternative climate state (BSC 2004 [DIRS 170042], Section 6.5). The 
scaling factor used in this approach is the ratio of average SZ groundwater flux under the future 
climatic conditions to the flux under present conditions. This approach approximates the impacts 
of future, wetter climatic conditions in which the SZ groundwater flux will be greater. However, 
this approach implicitly models the same flow path for radionuclide transport through the SZ 
under wetter climatic conditions of the future. In reality, significant rise in the water table due to 
climatic changes would result in different flow paths through the SZ system, including the 
potential for encountering different hydrogeologic units by radionuclides during transport. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-40 November 2004 
The objective of this modeling task is to adapt the SZ site-scale flow model to include the effects 
of estimated water table rise and to compare the results of particle-tracking simulations using this 
adapted model to the simple flux scaling approach used in TSPA analyses. Flow modeling for 
this task is presented in this report and the transport simulations are presented in BSC (2004 
[DIRS 170036], Sections 6.5 and 6.8). Based on qualitative arguments, the flux scaling 
approach to simulation of climate change is deemed to be conservative with regard to 
radionuclide transport in the SZ, relative to the more realistic situation in which water table rise 
is included in the modeling (BSC 2004 [DIRS 170042], Section 6.5). The purpose of this section 
is to both verify that assumption and provide an upper bound on the future climate fluxes. 
6.4.5.2.1 Estimating Water Table Rise from Climate Change 
Rise in the water table during wetter glacial transition conditions at Yucca Mountain is a 
complex function of greater recharge to the SZ and changes to the amount and spatial 
distribution of discharge from the regional SZ system. Simulations of groundwater flow under 
wetter, monsoonal conditions with the SZ regional-scale flow model (DAgnese et al. 1999 
[DIRS 120425]) indicate that groundwater flow paths from beneath Yucca Mountain do not 
change much under monsoonal conditions. These simulations also show that groundwater 
surface discharge from the SZ for the wetter monsoonal conditions would not occur along the 
flow path from Yucca Mountain at any location closer than the regulatory limit of approximately 
18 kilometers south of the repository. 
The estimated elevation of the water table under wetter, glacial transition conditions within the 
domain of the SZ site-scale flow model was calculated using the software code 
WTCONVYD V.1.00 STN: 10815-1.00-00 (SNL 2002 [DIRS 163835]). This software code 
uses an algorithm that incorporates qualitative information on the paleoflow system, an estimate 
of increased groundwater flux under glacial conditions based on known patterns of climatic 
cycles during the Quaternary period, particularly the last 500,000 years, and other paleoclimate 
data, and physical limits to the position of the water table. The software code calculates the 
estimated rise in the water table using this algorithm, along with data on the present water table 
surface and the elevations of the topographic surface. 
Estimates of the elevation of the water table under Yucca Mountain for wetter, glacial-transition 
climatic conditions indicate that the water table could have been on the order of 100 meters 
higher under these conditions based on the discussion in Section 6.4.5.1. The water table was 
calculated by the software code WTCONVYD assuming that water levels will rise 
approximately 100 meters higher than present conditions in the area beneath Yucca Mountain. 
In those areas of the model domain where the present water table has an elevation greater than 
730 meters (the approximate water level observed beneath Yucca Mountain), the software code 
also calculates the elevation of the water table under monsoonal conditions to be 100 meters 
higher than present conditions, except where the topographic surface is less than 100 meters 
above the present water table. This exception occurs in the canyon of Fortymile Wash in the 
northern part of the model domain where the software code calculates the water table under 
monsoonal conditions to occur within 1 meter of the topographic surface. There is little 
information upon which to base estimates of the water table configuration under monsoonal 
conditions in the area to the north of Yucca Mountain in the SZ site-scale flow model domain. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-41 November 2004 
However, the approach used in the software code WTCONVYD is reasonable and has little 
impact on the flow system downgradient of Yucca Mountain in the SZ site-scale flow model. 
Simulations of groundwater flow under wetter, glacial transition conditions with the SZ 
regional-scale flow model (DAgnese et al. 1999 [DIRS 120425]) indicate that the groundwater 
flux in the area of Yucca Mountain would be approximately four times greater than at present 
(see Section 6.6). The software code WTCONVYD calculates the higher water table elevations 
for monsoonal conditions such that the approximate hydraulic gradient would be greater by a 
factor of four for locations in the model domain where the present water table is between 
700 meters and 730 meters elevation. This range of water table elevations covers that portion of 
the SZ flow system along the flow path from beneath the repository to the regulatory limit of 
approximately 18 kilometers south of the repository. The approximation that the software code 
uses in this approach counts upon the average permeability along the flow path not differing 
significantly between present conditions and the monsoonal conditions and that a four-fold 
increase in the gradient would result in an approximately four-fold increase in the groundwater 
flux. Finally, the software code increases the elevation of the water table by a uniform value of 
10 meters for locations within the model domain where the present water table is less than 
700 meters elevation. This condition occurs only in the southern part of the SZ site-scale flow 
model domain where the water table is located in the valley-fill alluvium unit and the hydraulic 
gradient is relatively low. The elevation of the water table under monsoonal conditions is 
relatively unimportant with regard to the hydrogeologic unit configuration because of the thick 
alluvium in this area of the model domain. 
The software code WTCONVYD also limits the estimated rise in the water table under 
monsoonal conditions to within one meter of the topographic surface, which constitutes a 
physical limit to the rise in the water table within the domain of the SZ site-scale flow model. 
Rise of the water table to within one meter of the surface would induce significant groundwater 
discharge by evapotranspiration and the formation of local springs. 
The estimated elevations of the water table under wetter, monsoonal conditions, as calculated by 
the WTCONVYD are shown in Figure 6-11. Note that the pattern of the contours for the water 
table surface is generally similar to the present water table, with the exception of the area in 
Fortymile Canyon in the northern part of the model domain and in some areas in the 
south-central and southwestern parts of the model domain. These areas, in which the contours of 
the estimated higher water table are more irregular, are areas of shallow groundwater under 
monsoonal conditions. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-42 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
Source for repository outline: BSC 2003 (DIRS 162289). For illustration purposes only 
NOTE: Repository outline shown with bold blue line. 
UTM = Universal Transverse Mercator 
Figure 6-11. Estimated WaterTable Elevations for Future Glacial Transition Conditions 
Figure 6-12 shows the estimated depth to the water table under wetter, glacial transition climate 
conditions, as calculated by the WTCONVYD. The areas in which the estimated water table is 
within 5 meters of the topographic surface are shown with the light blue shading. The larger 
light-blue area of shallow estimated groundwater in the southwestern part of the domain contains 
the three areas of paleospring deposits located along U.S. Highway 95 and at the southern end of 
Crater Flat. This shows a certain degree of consistency between the estimated higher water table 
and the geologic features associated with Pleistocene spring discharge. The specific paleospring 
locations are probably controlled by structural features that are below the resolution of the 
analysis of the estimated water table elevation under monsoonal conditions. The other site of 
shallow estimated groundwater shown in Figure 6-12 is Fortymile Canyon. Although 
paleospring deposits are not observed in Fortymile Canyon, it is reasonable to postulate that such 
deposits would not be preserved in this geomorphic location. In any event, the large block sizes 
of the numerical model would average out heterogeneities of this scale. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-43 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
Source for repository outline: BSC 2003 (DIRS 162289). For illustration purposes only. 
NOTE: Repository outline shown with bold blue line. Areas with estimated depth to the water table of less than 5 m 
are shown with light blue shading. 
UTM = Universal Transverse Mercator 
Figure 6-12. Estimated Depth to the WaterTable for Future Glacial Transition Conditions 
In summary, a reasonable estimate of the water table elevation under wetter, glacial transition 
conditions is developed for the SZ site-scale flow model domain. The estimated rise in the water 
table is consistent with the estimated increase in groundwater flux along the inferred flow path 
from beneath the repository because the rise produces an approximately four-fold increase in 
hydraulic gradient. In addition, the pattern of the estimated rise in the water table is generally 
consistent with the locations of paleospring deposits within the domain. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-44 November 2004 
6.4.5.2.2 Water Table Rise in the SZ Site-Scale Flow Model 
The SZ site-scale flow model is adapted to the higher estimated water table for glacial transition 
conditions by creating a new grid with an upper surface corresponding to the higher water table. 
The lateral and bottom boundary locations remain the same in this adaptation of the model. The 
spatial distributions of hydrogeologic units at the water table in the flow model under present 
conditions and in the adapted model with the higher estimated water table are shown in 
Figures 6-13 and 6-14, respectively. 
Comparison of Figures 6-13 and 6-14 indicates potentially significant differences in the 
hydrogeologic units present in the shallow SZ beneath the repository and along the inferred flow 
path to the south and east of the repository at depths corresponding to the position of the water 
table at the different climatic conditions. The upper volcanic confining unit is much more widely 
distributed at the water table beneath the repository under estimated future monsoonal conditions 
than it is under present conditions, particularly under the northern and eastern parts of the 
repository. To the south and east of the repository, the alluvium unit is present at the water table 
over a broad area under estimated future conditions, where this unit is absent under the present 
conditions. 
The site-scale transport simulations with the higher water table are considered in BSC (2004 
[DIRS 170036], Section 6.6 and Appendix E1). Comparison of these simulations with the 
simplified approach used in TSPA abstraction shows that the site-scale transport model results in 
longer simulated transport times. The simplified TSPA approach is thus a conservative 
representation of transport in the SZ under wetter monsoonal conditions with regard to more 
realistic approach in which water table rise is included in modeling. 
6.4.6 Alternate SZ Site-scale Flow Model (Hydrogeologic Framework Model 
Reinterpretation and Additional Data) 
Additional data and analyses have become available after the SZ site-scale flow model was 
developed. These additional data and analyses include additional waterlevel data, a 
reinterpreted HFM, revised recharge distribution, updated boundary fluxes, additional 
permeability data, the use of 15 new Nye County head targets in some calibrations 
(DTN: MO0405NYE05819.215 [DIRS 170539]), and further evaluation of alternative 
conceptual models. To evaluate the impact of this additional knowledge on the modeling of the 
SZ site-scale flow system, an alternate SZ site-scale flow model has been formulated and 
calibrated. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-45 November 2004 
Source for repository outline: BSC 2003 (DIRS 162289). For illustration purposes only. 
NOTE: Repository outline shown with bold blue line. 
UTM = Universal Transverse Mercator 
Figure 6-13. Hydrogeologic Framework Model Units at the Water Table for Present Conditions 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-46 November 2004 
Source for repository outline: BSC 2003 [DIRS 162289]. For illustration purposes only. 
NOTE: Repository outline shown with bold blue line. 
UTM = Universal Transverse Mercator 
Figure 6-14. Hydrogeologic Framework Model Units at the Water Table for Estimated Future Glacial 
Transition Conditions 
6.4.6.1 Alternative Conceptual Model 
The conceptual model used in the alternate flow model has been modified from that used in the 
SZ site-scale flow model. Many of these changes are due to changes from the SZ site-scale flow 
model HFM conceptualization (DTN: GS030208312332.001 [DIRS 163087]) referred to as 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-47 November 2004 
HFM-19, which has 19 hydrogeologic units, to an updated version of the HFM conceptualization 
(DTN: GS021008312332.002 [DIRS 164363]) referred to as HFM-27 with 27 hydrogeologic 
units. The HFM-27 involves work associated with updates to the Death Valley regional flow 
model. In particular, a subset of the regional model was resampled and rebuilt at a finer 
resolution to be used for site-scale flow modeling. The Yucca Mountain HFM-19 has been 
reinterpreted with data obtained from the NC- EWDP and with the reinterpretation of existing 
data from other areas, including geophysical data in the northern area of the site. These changes 
are discussed in Section 6.4.6.2.3. 
The conceptual model used in the alternate flow model has also changed from that used in the SZ 
site-scale flow model, through the incorporation of an ACM for the LHG area north of Yucca 
Mountain. As discussed in Sections 6.4.1 and 6.7.1, a low-permeability eastwest feature has 
been incorporated into the SZ site-scale conceptual model north of Yucca Mountain to simulate 
the LHG area reflecting the postulated presence of a zone of hydrothermal alteration. However, 
there is little field evidence for the presence of this feature; but the Claim Canyon Caldera does 
exist north of Yucca Mountain. The Claim Canyon caldera is an area of extensive hydrothermal 
alteration that may result in a generalized reduction in permeability in the hydrogeologic units in 
this area. Alternate conceptualizations have been investigated that remove the extensive set of 
features north of Yucca Mountain but that divide the model domain along the Claim Canyon 
caldera into northern and southern zones, allowing different permeabilities to be assigned in the 
north versus the south within the same hydrogeologic unit. By creating a distributed region of 
lower permeability in the northern portion of the model, the LHG can be simulated in the flow 
domain. Using this basic conceptualization, several different conceptual models have been 
evaluated for the SZ site-scale flow model, but the conceptualization incorporating the 
northwestsoutheast-trending fault zone just north of Yucca Mountain and the Ghost Dance fault 
and the Dune Wash fault has been found to best reproduce water levels and flow paths from the 
repository. This alternative conceptualization has been identified as the altered with fault/Ghost 
Dance fault (AWF/GDF) conceptualization and has been used in the alternate flow model. A 
more detailed discussion regarding the evaluation of alternative conceptualizations is available in 
Section 6.7. 
6.4.6.2 Alternate Flow Model Formulation 
The mathematical formulation used in the alternate SZ site-scale flow model (Section 6-5) is 
identical to that used in the SZ site-scale flow model. The FEHM code (Zyvoloski et al. 1997 
[DIRS 100615]) was used in the SZ site-scale flow model to obtain a numerical solution to the 
mathematical equation describing groundwater flow. FEHM was used in the alternate flow 
model. However, the inputs used in the alternate flow model have been updated to reflect the 
increased data and analyses now available for formulating the SZ site-scale flow model. These 
changes in the model inputs are discussed below. 
6.4.6.2.1 Grid Generation 
The computational grid established for use in the alternate SZ site-scale flow model has been 
modified from that used in the SZ site-scale flow model (Section 6-6). The 500-meter horizontal 
grid spacing used in the SZ site-scale flow model has been retained in the alternate flow model. 
The grid is offset by 340 meters to the west and expanded by 500 meters in the eastwest 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-48 November 2004 
direction. The grid is offset by 280 meters to the south. The alternate flow model grid now 
coincides with even multiples of 100 meters in the UTM coordinate system. The result is a 
slightly larger grid. 
The grid for the alternate flow model has also been extended along the vertical coordinate to the 
ground surface, although those nodes located above the water table are not computationally 
active. A confined aquifer solution using the water table elevation to define the top of the flow 
system continues to be implemented as it was in the SZ site-scale flow model (Section 6-6). 
However, extension of the grid to the ground surface allows, if necessary, the simulation of a 
dynamic water table. The depth of the alternate flow model grid has also been extended to 
4,000 meters below sea level to match the depth of the HFM-27, which increased primarily to 
include more of the regional carbonate aquifer. Similar to the way in which the nodes above the 
water table are made computationally inactive, nodes a distance of 2,200 meters or greater below 
the variable-elevation water table are also removed from the computation. Thus, the active 
bottom of the alternate model grid varies from the north, where the water table is approximately 
1,200 meters above mean sea level, to the south, where the water table is approximately 
700 meters above mean sea level. This computational strategy was adopted in an effort to match 
the Death Valley regional flow model, which consists of three model layers, each with a constant 
thickness below a variable-elevation water table (DAgnese et al. 1997 [DIRS 100131], p 75). 
The vertical grid spacing of the alternate flow model is also equivalent to that of the site-scale 
flow model. Gridblocks higher than the 1,200 meters mentioned in Table 6-2, simply continue 
the 50-meter spacing listed for the top zone. Gridblocks lower than -600 meters have the 
400-meter vertical spacings. The gridblocks (nodes) increase from 142,853 nodes in the SZ 
site-scale flow model to 228,237 nodes in the alternate SZ site-scale flow model. This increase 
in number is due to the extension of the alternate SZ site-scale flow model grid to ground surface 
and its deeper extent. 
Table 6-2. Alternate SZ Site-Scale Flow Model and SZ Site-Scale Flow Model Size Comparison 
Alternate Flow 
Model 
HFM-27 
Alternate Flow 
Model 
Grid 
SZ Site-Scale 
Flow Model 
HFM-19 
SZ Site-Scale 
Flow Model Grid 
X 
min/max (UTM 
Easting, meters) 
533000563500 533000563500 533340563340 533340563340 
Y 
min/max (UTM 
Northing, meters) 
40465004091875 40465004091500 40467804091780 40467804091780 
Z 
min/max (datum mean 
seal level, meters) 
-41002156 -40002150 -23551343 -22001200 
Nodes 2140320 228237 1827021 142853 
Source DTN: GS021008312332.002 [DIRS 164363], SZ site-scale flow model HFM-27 
DTN: GS030208312332.001 [DIRS 163087], SZ site-scale flow model HFM-19 
DTN: LA0304TM831231.002 [DIRS 163788] SZ site-scale flow model grid. 
NOTE: HFM = hydrogeologic framework model; SZ = saturated zone; UTM = Universal Transverse Mercator 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-49 November 2004 
6.4.6.2.2 Hydrogeologic Framework Model 
Since the development of the HFM-19 used in the SZ site-scale flow model, the Yucca Mountain 
HFM has been reinterpreted with data recently obtained from the EWDP and through the 
reinterpretation of existing data from other areas, including geophysical data in the northern area 
of the site. The major changes in the southern part of the model are the depths and extent of the 
alluvial layers. The HFM for the northern part of the model domain has also changed 
substantially. This is largely the result of reinterpretation of geophysical data regarding the 
depth of the carbonate aquifer. The reinterpretation results in the shape and extent of the 
carbonate aquifer changing significantly. In particular, the carbonate aquifer is no longer 
believed to intersect the northern boundary of the SZ site-scale flow model. 
Because of the reinterpretation of the HFM-19, the number and distribution of hydrogeologic 
units has been modified in the HFM-27 that is used in the alternate flow model. A comparison 
of the hydrogeologic units identified in the HFMs used in the SZ site-scale flow model and 
alternate flow models is provided in Table 6-3, which indicates that while there were 
19 hydrogeologic units in the SZ site-scale flow model HFM-19, there are 27 hydrogeologic 
units in the alternate HFM-27. Four of the 27 units present in the regional model are not 
represented in the site-scale HFM because these units are pinched out by adjacent units. The 
alternate grid covers a slightly larger area horizontally and extends from the surface to a deeper 
elevation than the SZ site-scale flow model grid. In order to compare the alternate and site-scale 
grids, the larger alternate is subset to the volume occupied by the full SZ site-scale flow model 
grid. Because the two grids do not have elements aligned, there is a minimum subset, fully 
enclosed by the SZ site-scale flow model grid, and a maximum subset, slightly larger than the 
volume of the SZ site-scale flow model grid. Table 6-4 lists the number of nodes in each unit for 
the grids. This table also gives the percentage volume for each of the hydrogeologic units. 
To provide a better understanding of the changes in the HFM-27 used for the alternate SZ 
site-scale flow model, discussions comparing the differences in the hydrogeology at the water 
table, in the area of Nye County, and along the anticipated flow path from the repository are 
provided in the next sections. 
Table 6-3. Correlation of Alternate SZ Site-Scale Flow Model HFM-27 and SZ Site-Scale Flow Model 
HFM-19 Units 
Alternate Flow Model SZ Site-Scale Flow Model 
Abbreviation Hydrogeologic Name Unit Unit Hydrogeologic Name 
Base Base (-4000 m) 1 1 Base (bottom of regional flow model) 
ICU Intrusive Confining Unit 2 2 Granitic confining unit (granites) 
XCU Crystalline Confining Unit 3 3 Lower Clastic Confining Unit (lccu) 
LCCU Lower Clastic Confining Unit 4 3 Lower Clastic Confining Unit (lccu) 
LCA Lower Carbonate Aquifer 5 4 Lower Carbonate Aquifer (lca) 
UCCU Upper Clastic Confining Unit 6 5 Upper Clastic Confining Unit, Upper Clastic 
Confining Unit  thrust 2 (uccu, uccut2) 
UCA Upper Carbonate Aquifer 7 7 NA 
LCCU_T1 Lower Clastic Confining Unit - 
thrust 
8 NA Lower Clastic Confining Unit - thrust 1 (lccut1) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-50 November 2004 
Table 6-3. Correlation of Alternate SZ Site-Scale Flow Model HFM-27 and SZ Site-Scale Flow Model 
HFM-19 Units (Continued) 
Alternate flow model SZ site-scale flow model 
Abbreviation Hydrogeologic Name Unit Unit Hydrogeologic Name 
LCA_T1 Lower Carbonate Aquifer - 
thrust 
9 6 Lower Carbonate Aquifer thrusts 1 and 2 
(lcat1, lcat2) 
SCU Sedimentary Confining Unit 
(none in site area) 
NA NA NA 
VSU Lower Lower Volcanic and 
Sedimentary Units 
11 8 Undifferentiated valley-fill (leaky) 
OVU Older Volcanic Units 12 9,10,11 Older Volcanic Confining Unit, Older Volcanic 
Aquifer, Lower Volcanic Confining Unit (lvcu, 
lva, mvcu) 
BRU Belted Range Unit (none in site 
area) 
NA NA NA 
CFTA Crater Flat - Tram Aquifer 14 12 Lower Volcanic Aquifer  Tram Tuff (tct) 
CFBCU Crater Flat - Bullfrog Confining 
Unit 
15 13 Lower Volcanic Aquifer Bullfrog Tuff (tcb) 
CFPPA Crater Flat - Prow Pass Aquifer 16 14 Lower Volcanic Aquifer Prow Pass Tuff (tcp) 
WVU Wahmonie Volcanic Unit 17 15 Upper Volcanic Confining Unit (uvcu) 
CHVU Calico Hills Volcanic Unit 18 15 Upper Volcanic Confining Unit (uvcu) 
PVA Paintbrush Volcanic Aquifer 19 16 Upper Volcanic Aquifer (uva) 
TMVA Timber Mountain Volcanic 
Aquifer 
20 16 Upper Volcanic Aquifer (uva) 
Alternate flow model SZ site-scale flow model 
Abbreviation Hydrogeologic Name Unit Unit Hydrogeologic Name 
VSU Volcanic and Sedimentary 
Units 
21 8 Undifferentiated valley-fill (leaky) 
YVU Young Volcanic Units (none in 
site area) 
NA NA NA 
LFU Lavaflow Unit 23 17 Lava-flow Aquifer (basalts) 
LA Limestone Aquifer 24 18 Limestone Aquifer (amarls) 
OACU Older Alluvial Confining Unit 
(none in site area) 
NA NA NA 
OAA Older Alluvial Aquifer 26 20 Valley-fill Aquifer (alluvium), Undifferentiated 
valley-fill (leaky) 
YACU Young Alluvial Confining Unit 27 19 Valley-fill Confining Unit (playas) 
YAA Young Alluvial Aquifer 28 20 Valley-fill Aquifer (alluvium) 
NOTE: These units do not have a one-to-one correlation. This table approximately relates the alternate HFM 
hydrogeologic units to the SZ site-scale flow model HFM hydrogeologic units. Four units do not occur in the 
site-scale HFM (OACU, YVU, BRU, and SCU) but are included to maintain the relationship to the regional 
model. 
Sources for these data are: DTN: GS021008312332.002 [DIRS 164363] for HFM-27 (alternate conceptual 
models HFM) and DTN: GS030208312332.001 [DIRS 163087] for HFM-19 (base case HFM). The details 
of implementations are provided in BSC (2004 [DIRS 170008]). 
HFM = hydrogeologic framework model; N/A = not applicable; SZ = saturated zone 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-51 November 2004 
Table 6-4. Comparison of Grid Hydrogeologic Unit Volume: Alternate SZ Site-Scale Model vs. SZ Site- 
Scale Flow Model 
Unit Name Alternate flow model SZ site-scale flow model 
Unit ID Nodes Fractional Volume Unit ID Nodes Fractional Volume 
ICU 2 5304 0.06155 2 608 0.00668 
XCU 3 2470 0.02863 
LCCU 4 12726 0.13700 
3 
13259 
0.17918 
LCA 5 31835 0.34402 4 27097 0.39315 
UCCU 6 10648 0.03995 5 5923 0.05606 
UCA 7 1278 0.00150 7 23 0.00001 
LCCU_T1 8 5074 0.04009 NA 0 0 
LCA_T1 9 9000 0.06111 6 1192 0.01087 
VSU Lower 11 21411 0.11172 
VSU Upper 21 9435 0.00850 
8 
21578 
0.14526 
OVU 12 5663 0.02432 
9 
10 
11 
11012 
210 
9142 
0.06112 
0.00238 
0.03868 
CFTA 14 22626 0.04429 12 11676 0.03551 
CFBCU 15 12829 0.01708 13 6472 0.01373 
CFPPA 16 6185 0.00698 14 5666 0.01101 
WVU 17 4484 0.00412 
CHVU 18 15403 0.01892 
15 
7845 
0.01261 
PVA 19 33544 0.03709 
16 
13831 
0.02389 
TMVA 20 6083 0.00608 
LFU 23 2104 0.00175 17 891 0.00095 
LA 24 1050 0.00044 18 227 0.00042 
YACU 27 286 0.00010 19 13 0.00002 
OAA 26 5024 0.00319 
YAA 28 3775 0.00157 
20 
6188 
0.00846 
NOTE: These units do not have a one-to-one correlation. Table 6-3 provides further detail of the units correlation. 
This table relates the alternate HFM hydrogeologic units to the SZ site-scale flow model HFM hydrogeologic 
units. 
Sources for these data are: DTN GS021008312332.002 [DIRS 164363] for HFM-27 (alternate conceptual 
models HFM) and DTN GS030208312332.001 [DIRS 163087] for HFM-19 (base- case HFM). The details of 
implementations are provided in BSC (2004 [DIRS 170008]). 
HFM = hydrogeologic framework model; N/A = not applicable; SZ = saturated zone 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-52 November 2004 
6.4.6.2.2.1 Comparison of Hydrogeology at the Water Table 
A comparison of hydrogeologic units present at the water table in the site-scale flow model 
HFM-27 is presented in Figure 6-15. As shown in both parts of this figure, major differences are 
evident in the southern part of the model where the volcanic and sedimentary units replace the 
valley-fill aquifer as the most pervasive unit in the revised HFM-27. The -most zone, called the 
alluvial uncertainty zone, represents a transition zone from the volcanic to the alluvial aquifer 
system. It replaces the older HFM-19 because, based on logs from well NC-EWDP-19-D, the 
alluvial aquifer extended north farther than what is presented in the HFM-19. The permeability 
associated with this zone is a calibration parameter and, thus, can represent either aquifer system. 
A second zone, the lower Fortymile Wash zone, was inserted to achieve a better calibration in 
the alternate model. It represents a distinct subset of the alluvial aquifer that is characterized by 
the higher proportion of gravels in the lower-most portion of Fortymile Wash. The Calico Hills 
volcanic unit has replaced the upper volcanic confining unit in the HFM-27. In the HFM-27, 
there is no longer any of this Calico Hills material separating the upper and lower portions of the 
Fortymile Wash. Further north, the Paintbrush volcanic aquifer replaces the upper volcanic 
aquifer as the dominant unit, at least near the water table. The Yucca Mountain block remains 
comprised of the Crater Flat group: Prow Pass, Bullfrog, and Tram units. The Crater Flat units 
are more continuous to the north and west of Yucca Mountain in the HFM-27 than in the 
HFM-19. Because the Crater Flat group has relatively high permeability, the new representation 
may provide a high-permeability flow path at the water table to Yucca Mountain that was not 
present in the earlier model. To be able to examine flow paths through the geologic units only 
three particles P1, P50, and P100 for the left figure and P6, P50, and P100 for the right figure are 
used to compare the flow paths at the water table. One of the revealed differences between the 
two HFMs and their respective flow models is that particle P1 did not travel along the water 
table in the alternate model as it did in the case of the SZ site-scale flow model. Another particle 
P6 was used in the alternate model. The purpose of tracking the 3 particles is to show clear 
single paths in units through which the flow paths travel which is not possible to do when 
showing all 100-particle paths. 
6.4.6.2.2.2 Comparison of Nye County Hydrogeology 
The most pronounced difference between HFM-19 and HFM-27 is the relative abundance of the 
Crater Flat group (given by the reds and yellows) to the west of Yucca Mountain in the HFM-27. 
The Crater Flat group represents relatively high permeability rock. However, the flow paths of 
fluid particles leaving the repository area are expected to be to the east of Yucca Mountain. 
Thus, this change in the HFM may not significantly influence the alternate SZ site-scale flow 
models ability to replicate the flow paths predicted by the SZ site-scale flow model. In the 
HFM-27, the Crater Flat group is more continuous on the east side of Yucca Mountain, possibly 
influencing the calibration and specific discharge predictions of the alternate flow model. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-53 November 2004 
Source: DTN: GS030208312332.001 (DIRS 163087); DTN: GS021008312332.002 (DIRS 164363). 
NOTE: The material units in these two models do not have a one-to-one correlation an approximate relationship is inferred with the color bar and unit names. See 
also Table 6-3. 
UTM = Universal Transverse Mercator 
Figure 6-15. Hydrogeology and Selected Particle Paths at the Water Table for Base Case and Alternate Models 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-54 November 2004 
6.4.6.2.3 Features 
A set of 17 hydrogeologic features was incorporated into the SZ site-scale flow model. In the 
alternate SZ site-scale flow model, these features have been modified, largely due to changes 
necessary to incorporate an ACM for the LHG north of Yucca Mountain. The alternative 
conceptualization, which is referred to as the AWF/GDF conceptualization of the LHG area in 
Section 6.7.1, has been used in the alternate SZ site-scale flow model. The AWF/GDF 
conceptualization does not make use of the extensive feature set north of Yucca Mountain, and 
these have been removed from the model grid, thereby simplifying the grid used in the alternate 
SZ site-scale flow model. Instead, the hydrogeologic units have been divided into northern and 
southern zones at the Claim Canyon caldera boundary to represent a zone of hydrothermal 
alteration in the area of the caldera. Differ permeabilities can be assigned in each zone to each 
hydrogeologic unit. In addition, a zone has been added to represent the northwest-southeast 
trending fault zone just north of Yucca Mountain, and features have been added to account for 
the Ghost Dance fault and the Dune Wash fault. Although there are fewer discrete features in the 
alternate SZ site-scale flow model than in the SZ site-scale flow model, there are actually a 
greater number of calibration parameters. This increase in the number of parameters is a result 
of breaking the hydrogeologic units into northern and southern zones. In addition, the alluvial 
uncertainty zone has been removed as a feature in the alternate SZ site-scale flow model. The 
location of each of these features is depicted in Figure 6-16. The gray zones were defined for the 
SZ site-scale flow model and are described in Table 6-6. The table also describes the colored 
zones added to represent features in the alternate flow model. 
6.4.6.2.4 Boundary Conditions 
The boundary conditions were established in the alternate SZ site-scale flow model in the same 
manner as in the SZ site-scale flow model (Section 6-6). Constant head boundaries were 
established around the periphery of the model at each boundary node. However, in the case of 
the alternate flow model, the updated 2001 potentiometric surface (BSC 2004 [DIRS 170009]) 
has been used to identify the water levels specified at each boundary node. Identical to the SZ 
site-scale flow model, the heads remain constant with depth at each boundary nodal point and, 
consequently, vertical flow is not allowed along the boundary of the alternate SZ site-scale flow 
model. 
6.4.6.2.5 Recharge 
Recharge was applied to the top surface of the computational grid as a flux boundary condition 
in the alternate flow model in a manner to that in the SZ site-scale flow model. However, an 
updated recharge distribution (DTN: SN0407T0504404.002 [DIRS 170929]) as described in 
BSC (2004 [DIRS 170015]) has been used in the alternate SZ site-scale flow model. The update 
recharge distribution results in similar recharge to the alternate SZ site-scale flow model.
MDL-NBS-HS-000011 REV 02 6-55 November 2004 
Saturated Zone Site-Scale Flow Model 
Sources: DTN GS021008312332.002 (DIRS 164363) for HFM-27 (revised HFM) and DTN GS030208312332.001 (DIRS 163087) for HFM-19 (base case HFM). 
The details of implementations are provided in the HFM report (BSC 2004 [DIRS 170008]). 
NOTE: SZ model representation of features zoomed in to the area north of Y= 4060000. The gray zones were defined for the SZ site-scale flow model and are 
described in Table 6-6. These colored zones are added to represent features in the alternate flow models and are described in Table 6-6. 
SZ = saturated zone; UTM = Universal Transverse Mercator. 
Figure 6-16. Geologic Features in the SZ Area for the Alternate Flow Models 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-56 November 2004 
6.4.6.3 Calibration of Alternate SZ Site-Scale Flow Model 
The alternate SZ site-scale flow model was calibrated with consideration of the full range of 
currently available data, including field data for water levels and hydraulic heads, permeability 
data from field and laboratory tests, locations of known faults and other geologic data, and 
hydrochemical data. Calibration is the process by which values of important model parameters 
are estimated and optimized to produce the best fit between the model output and the observed 
data. Following the same philosophy used to calibrate the SZ site-scale flow model; the alternate 
SZ site-scale flow model was calibrated to deliver a model that is realistic where data exist and 
conservative where data are lacking. Besides these objectives, the alternate SZ site-scale flow 
model was also used to address parameter sensitivity, the impact of the new Nye County 
water-level data, and the uncertainty in groundwater flux in the model and the propagation of 
uncertainty from the regional DVRFS to the site scale flow model. A total of five calibrations 
were necessary to address these issues. The calibration of the alternate flow model was 
automated using the PEST code in a manner similar to that used during the calibration of the SZ 
site-scale flow model. 
6.4.6.3.1 Calibration Targets 
In a manner similar to the calibration of the SZ site-scale flow model (Section 6-6), water levels 
and boundary fluxes were used as calibration targets during the calibration of the alternate SZ 
site-scale flow model. However, during the alternate SZ site-scale flow model calibration, the 
water levels used as calibration targets during the SZ site-scale flow model calibration were 
augmented by new waterlevel data obtained from wells recently installed as part of the EWDP. 
The location of these new wells is shown in Figure 6-17. A total of 26 waterlevel 
measurements are now available in Nye County, bringing the number of waterlevel 
measurements used as targets during the calibration of the alternate SZ site-scale flow model to 
130. Uncertainty resulting from the spatial distribution of observation wells is discussed in the 
hydrogeologic framework model report (BSC 2004 [DIRS 170008]). 
Because of the potential importance of flux and fluid path lines on specific discharge (and by 
inference on radionuclide transport), additional effort is expended on flux targets. 
Fluxes around the boundary of the model domain have again been used as calibration targets 
during the calibration of the alternate SZ site-scale flow model. The fluxes used in the site-scale 
flow model were based on fluxes derived from the 1997 DVRFS model (DAgnese et al. 1997 
[DIRS 100131]). However, since 1997, the DVRFS model has been updated and undergone 
significant improvements, including an increased resolution in the vertical dimension, with the 
number of vertical layers increasing from 3 in the 1997 model to 15 in the updated 2001 DVRFS 
model (DAgnese et al. 2002 [DIRS 158876]). In addition, the 1997 DVFRS model used a 
concept of permeability classes, while node-specific values of permeability are assigned in the 
updated DVRFS model. Due to these and other enhancements, the updated 2001 DVRFS model 
offers improved estimates of fluxes along the boundary of the SZ site-scale flow model and has 
been used to establish boundary flux targets for the alternate SZ site-scale flow model. A 
comparison of the boundary fluxes used in the SZ site-scale flow model and alternate SZ 
site-scale flow models is presented in Section 6.4.6.4. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-57 November 2004 
As shown in Section 6.4.6.4, the flux targets have changed from the SZ site-scale flow model to 
the alternate SZ site-scale flow model. The biggest differences occur on the east and west sides 
of the SZ site-scale flow model. In particular, the thrust zone in the southeastern corner of the 
model has been removed in DAgnese et al. (2002 [DIRS 158876]). As a result, the flux target 
has decreased from -555 kg/s (-1.8  107 m3/yr) to -69.7 kg/s (-2.2  106 m3/yr) in the 
southern-most zone on the eastern boundary. Overall, the flow out of the southern boundary in 
the alternate SZ site-scale flow model is approximately one-half (430/918) of the flux in the SZ 
site-scale flow model. The large differences in the flux targets can be traced to the evolution of 
the DVRFS model. 
At the time the SZ site-scale flow model was developed and calibrated, the DVRFS model 
consisted of three vertical layers (DAgnese et al. 1997 [DIRS 100131]). The SZ site-scale flow 
model had 39 vertical layers. This fact, and the fact that the HFMs used to generate the 1997 
DVRFS and the SZ site-scale flow models were different, made it difficult to match flux targets 
in the SZ site-scale flow model. For example, on the southwestern side of the SZ site-scale flow 
model, the SZ site-scale flow model HFM showed a large quantity of clastic confining material 
that made it difficult to match the -71 kg/s (-2.2  106 m3/yr) (west boundary, SZ site-scale flow 
model) derived from the regional model. The vertical resolution of the DVRFS model 
(DAgnese et al. 2002 [DIRS 158876]) has now increased dramatically, and the HFMs used in 
the site-scale and regional flow models are now much closer. It is also important to note, 
however, that the HFM-27 has undergone considerable checking and revision, resulting in 
changes in the HFM-27 in the areas of upper and lower Fortymile Wash that may affect flows 
within the SZ site-scale flow model. Despite these differences, the flux targets listed in 
Section 6.4.6.4 for the alternate flow model should be more realistic and, consequently, more 
achievable than those for the SZ site-scale flow model because the regional and site-scale HFMs 
are more compatible. The eastern boundary fluxes were extracted at 563,000 meters instead of 
the model boundary of 563,500 meters. This is 500 meters west of the actual model boundary. 
The error in the fluxes boundary value caused by the offset is proportional to the change in 
gradient between the two locations. A visual examination of the potentiometric surface indicates 
small gradient variation between the two locations. The boundary flux error is within the 
uncertainty in the boundary flux that was investigated. 
In order to address uncertainty in flow path lines due to uncertainty in the boundary fluxes, 
different arrangement of flux targets were investigated in the calibrations (Table 6-5). The 
uncertainty was addressed by using the changes in the fluxes derived from the DVRFS as 
surrogates for the flux uncertainty. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-58 November 2004 
Source DTN: GS010908312332.002 (DIRS 163555). 
NOTE: Numbers in the figure refer to the well numbers listed in the second column of Table 6-7 Red symbols are 
wells used for the SZ site-scale flow model. Wells added to the Alternate flow models are the green 
Northeast constraining wells, and blue Nye-County wells (phase 1 and 2) numbers 120 to 134. The crosses 
indicate weights of 1, diamonds are weights 4 and 9, and the square at well 93 is weight 10. 
UTM = Universal Transverse Mercator. 
Figure 6-17. Location and Weights of Observation Wells for SZ Site-Scale Flow Model and Alternate 
Flow Models 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-59 November 2004 
Table 6-5. Alternate SZ Site-Scale Flow Models Descriptions 
Flow Model Base Case AM0 AM1 AM2 AM3 AM4 
HFM HFM-19 HFM-27 HFM-27 HFM-27 HFM-27 HFM-27 
Nye County Wells 
Used in Calibration 
No Yes No Yes Yes Yes 
Boundary Flux, 
single or multiple 
targets per side 
Multiple Single Single Multiple Single Single 
Boundary Flux Table 6-12 
values 
Table 6-12 
values 
Table 6-12 
values, 
Table 6-12 
values, 
Table 6-12 
values 
except west 
side target 
of -119 kg/s 
Table 6-12 
values 
except east 
side target 
of -96 kg/s 
Sources: DTNs: GS021008312332.002 (DIRS 164363) for HFM-27 (alternate conceptual models HFM) and 
GS030208312332.001 (DIRS 163087) for HFM-19 (base case HFM). The details of the HFM 
implementations are provided in the HFM (BSC 2004 [DIRS 170008]). 
AM = alternate model; HFM = hydrogeologic framework model. 
AM0 Alternate Site-Scale Flow Model 0: This model is the standard in which the fluxes listed 
in Section 6.4.6.4 are used for the alternate SZ site-scale flow model. There is one major 
difference. Instead of using the spatially distributed zones listed in the table, the fluxes on each 
side boundary were summed and used as a single target for each side. This was justified by the 
very large uncertainty and differences in gridding. The multiple flux target model is evaluated in 
alternate flow model 2. 
AM1 Alternate Site-Scale Flow Model 1, Nye County Targets: This model is the same as 
AM0, however it does not use the 15 new Nye County well water levels that were available after 
the SZ site-scale flow model was created. It quantifies how these additional data affect the 
alternate flow model (by comparison to AM0) and by inference, the SZ site-scale flow model. 
AM2 Alternate Site-Scale Flow Model 2, Multiple Flux Targets: This model is the same as 
AM0, only it uses the distributed flux targets given in Section 6.4.6.4. This calibration 
distinguishes the differences between one per side flux targets of AM0 and the multiple targets 
of this calibration. 
AM3 Alternate Site-Scale Flow Model 3, West Flux Changed: The SZ site-scale flow model 
did not use flux targets on the west side because of differences between the site HFM and 
regional HFM. We note here that the flux changed from -119 kg/s (in) to 125 kg/s (out), a 
change of 200 percent. This fact necessitated the exploration of flux uncertainty on the west 
side. AM3 uses a flux target on the west side of -11 kg/s instead of 125 kg/s that is used on 
AM0. 
AM4 Alternate Site-Scale Flow Model 4, Small East Flux: The flux on the east side has 
potentially a large impact on the flow path lines since the SZ site-scale flow model has path lines 
(starting from the repository) that traverse parts of Fortymile Wash. This alternate flow model 
uses a flux target of -96 kg/s instead of the -209 kg/s. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-60 November 2004 
Figure 6-17 shows the wells used for the calibration targets of the alternate flow model. In the 
figure, the Nye County targets are highlighted. Section 6.4.6.4 summarizes the flux targets for 
each of the alternate flow model calibrations. 
As was the case for the SZ site-scale flow model, calibration targets along the potential flow path 
are given higher weights. However, in the alternate flow model moderate gradient wells, and 
those in lower Fortymile Wash, if they were along the flow path, were given higher weights as 
well as the low gradient wells (which were the only higher-weighted wells in the SZ site-scale 
flow model). Other weightings were similar to the SZ site-scale flow model, 
DTN: GS010908312332.001 [DIRS 163087] (see Section 6.6.1.3). 
The higher weights were given to wells that were thought to be in the possible flow path. The 
weighting was changed between the base case and the alternate flow models AM0 and AM4 
largely because of additional data collected from the Nye county wells. More wells were added 
by Nye County along the projected flow path. 
6.4.6.3.2 Calibration Parameters 
In a manner similar to the SZ site-scale flow model (Section 6-6), permeability was optimized 
during calibration of the alternate SZ site-scale flow model. Permeability zones were created for 
hydrogeologic units identified in HFM-27 and for specific hydrogeologic features established in 
the model. In the SZ site-scale flow model, a permeability zone was established for each 
hydrogeologic unit, with the exception of the basal unit that served as a lower boundary for the 
model. The permeability parameters used in the alternate SZ site-scale flow models are those 
described in Section 6.4.1, on the LHG ACM. The alternate SZ site-scale flow model also uses 
additional zones and features for purposes of calibration and exploration of flow path line 
uncertainty. These are summarized below. 
 A permeability zone was created for each hydrogeologic unit present in the Claim 
Canyon caldera to allow for modifying unit permeabilities in this area. This 
modification was necessary to implement the ACM used to simulate the LHG area in the 
north of the model domain (see Section 6.4.6.2.4). 
 A permeability zone was created for each member of the Crater Flat group (Tram, 
Bullfrog, and Prow Pass) near Yucca Mountain. This modification was used to explore 
spatial differences in this hydrogeologic group between the low head gradient area east 
of Yucca Mountain and the Yucca Mountain area itself. 
 Permeability zones were created for several of the deeper units near the east side of the 
SZ site-scale flow model. The affected units are the intrusive (granitic confining), lower 
carbonate, lower clastic, and lower carbonate thrust. These zones were created in order 
to study flux uncertainty on the east boundary of the site model. 
It should also be noted that the alluvial uncertainty zone, an important zone in SZ site-scale flow 
model, has been removed for the alternate SZ site-scale flow model. The rationale for using the 
zone, an inability of HFM-19 to represent the hydrogeology near the Alluvial Testing Complex, 
has been corrected. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-61 November 2004 
Upper and lower bounds were placed on each permeability variable during parameter 
optimization, as occurred in the SZ site-scale flow model. The upper and lower bounds for the 
permeabilities and permeability multipliers were chosen to reflect maximum and minimum field 
values (permeability) or a reasonably realistic range of values (permeability multipliers). These 
limits reflected all data available at the time of model calibration, including new permeability 
data obtained since the calibration of the SZ site-scale flow model. A list of permeability zones, 
including the parameter type assigned to each zone, the upper and lower bounds specified for the 
parameter, and an identification of the parameters optimized during calibration, is provided in 
Table 6-8. In a manner similar to the SZ site-scale flow model, the vertical anisotropy was 
assigned a value of 10:1 (horizontal to vertical) in the volcanic and valley-fill units in the 
alternate SZ site-scale flow model. The location of each of these features is depicted in 
Figure 6-16. The gray zones were defined for the site-scale flow model and are described in 
Table 6-6. The table also describes the colored zones added to represent features in the alternate 
flow models. 
Table 6-6. Hydrological Features in the SZ Alternate Flow Model 
Feature Name and 
Description 
Geometric Definition 
(x, y UTM meters, 
z, elevation above msl, meters) 
Hydrogeological 
Characteristics Impact on Model 
1. Eastern Flux 
Zone 
This region 
adjacent to the 
eastern boundary 
allows the 
properties of some 
of the regional 
hydrogeologic units 
to vary spatially. 
xmin = 555000 
xmax = 563500 
ymin = 4065000 
ymax = 4080000 
z = entire model 
This zone affects the flux 
entering the model on the 
east side. 
Although it does not 
strongly influence the flow 
model, it is expected to be 
important to performance 
assessment calculations 
due to its effect on solute 
transport. 
2. Yucca 
Mountain Crater 
Flat Zone 
Due to different 
geologic 
environments near 
Yucca Mountain 
and removed from 
Yucca Mountain. 
The Tram, Bullfrog, 
and Prow Pass 
units are allowed 
different parameter 
values near Yucca 
Mountain. 
xmin = 544000 
xmax = 548000 
ymin = 4070000 
ymax = 4085000 
Z = entire model 
These parameters are 
important to flow near 
Yucca Mountain. 
It allows representation of 
permeability near Yucca 
Mountain that may be 
different from other areas of 
the site scale model. 
3.Dune Wash 
Fault 
This fault is 
potentially 
important to flow 
near Yucca 
Mountain. 
xmin = 548800 
xmax = 551400 
ymin = 4076000 
ymax = 4072000 
zmin = 400 
zmax = top of model 
Possible control of fluid 
pathways near Yucca 
Mountain. 
Fault is a possible 
preferential flow path. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-62 November 2004 
Table 6-6. Hydrological Features in the SZ Alternate Flow Model (Continued) 
Feature Name and 
Description 
Geometric Definition 
(x, y UTM meters, 
z, elevation above msl, meters) 
Hydrogeological 
Characteristics Impact on Model 
4.Ghost Dance 
Fault 
Linear feature that 
intersects the 
repository area. 
xmin = 547960 
xmax = 548210 
ymin = 4072000 
ymax = 4080000 
zmin = 400 
zmax = top of model 
Control of fluid pathways 
near the repository. 
Fault is a possible 
preferential flow path. 
Source for these data is: DTN GS021008312332.002 [DIRS 164363] for HFM-27 (alternate conceptual models 
HFM). The details of implementations are provided in BSC (2004 [170008]). 
NOTE: msl = mean sea level; UTM = Universal Transverse Mercator 
6.4.6.3.3 Calibration Results: Heads and Fluxes 
Calibrations were achieved for all alternate SZ site-scale flow models (AM0, AM1, AM2, AM3, 
and AM4). The calibration results are presented in Table 6-7 for the head comparisons and 
Table 6-12 for the boundary flux comparisons. Ten target observations that fall above the 
simulated water table are noted in Table 6-7. Because of the fine resolution of the grid at the 
water table, the elevations of these points fall above the water table and therefore were 
eliminated from use as calibration targets. These observation points are located next to other 
observation points used as calibration targets; therefore, their elimination did not diminish the 
accuracy of the calibration. The SZ site-scale flow model assigned these target positions to the 
top layer of the model. 
Table 6-7. Calibration Results: Observed WaterLevel Elevation vs. Calibrated Head for Alternate SZ 
Site-Scale Flow Models AM0, AM1, AM2, AM3, and AM4 
Site Name 
Well 
Number 
Water 
Level 
(m) 
Head 
Model 
AM0 (m) 
Head 
Model 
AM1 (m) 
Head 
Model 
AM2 (m) 
Head 
Model 
AM3 (m) 
Head 
Model 
AM4 (m) 
UE-29 a #2 1 1187.7 1249.24 1251.17 1226.44 1243.7 1240.59 
GEXA Well 4 2 1008 1005.72 1005.69 1001.38 1008.33 1009.37 
UE-25 WT#6 3 1034.6 740.68 741.33 749.84 747.35 747.73 
USW G-2 4 1020.2 748.26 749.45 753.93 756.1 753.99 
UE-25 WT #16 5 738.3 735.74 735.93 741.07 740.24 740.57 
USW UZ-14 6 779 AWT AWT AWT AWT AWT 
UE-25 WT #18 7 730.8 735.88 736.29 737.22 738.94 738.04 
USW G-1 8 754.2 749.96 750.75 750.93 754.06 751.07 
UE-25 a #3 9 748.3 750.16 749.93 750.21 751.99 749.84 
UE-25 WT #4 10 730.8 732.53 732.68 734.7 735.08 734.51 
UE-25 WT #15 11 729.2 729.65 729.53 729.76 730.08 729.34 
USW G-4 12 730.6 729.88 729.91 729.83 730.79 729.87 
UE-25 a #1 13 731 730.09 730.12 730.33 731.19 730.25 
UE-25 WT #14 14 729.7 729.7 729.63 729.96 730.42 729.71 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-63 November 2004 
Table 6-7. Calibration Results: Observed WaterLevel Elevation vs. Calibrated Head for Alternate SZ 
Site-Scale Flow Models AM0, AM1, AM2, AM3, and AM4 (Continued) 
Site Name 
Well 
Number 
Water 
Level 
(m) 
Head 
Model 
AM0 (m) 
Head 
Model 
AM1 (m) 
Head 
Model 
AM2 (m) 
Head 
Model 
AM3 (m) 
Head 
Model 
AM4 (m) 
USW WT-2 15 730.6 729.7 729.71 729.61 730.6 729.75 
UE-25 c #1 16 730.3 729.62a 729.59a 729.77a 730.51a 729.81a 
UE-25 c #3 17 730.3 729.62a 729.59a 729.77a 730.51a 729.81a 
UE-25 c #2 18 730.2 729.62 729.58 729.77 730.51 729.8 
UE-25 WT #13 19 729.1 729.53 729.42 729.6 730 729.3 
USW WT-7 20 775.8 778.79 780.17 779.59 785.39 779.49 
USW WT-1 21 730.4 729.47 729.42 729.57 730.34 729.59 
USW G-3 22 730.5 730.06 730.04 730.08 730.97 730.28 
UE-25 J-13 23 728.4 729.31 729.22 729.34 729.84 729.22 
USW WT-10 24 776 771.23 772.85 772.67 779.35 772.03 
UE-25 WT #17 25 729.7 729.12 729.03 729.25 729.88 729.34 
USW VH-2 26 810.5 806.09 807.6 807.5 810.68 808.49 
UE-25 WT #3 27 729.6 729.08 728.97 729.16 729.63 729.03 
USW VH-1 28 779.4 775.93 777.42 776.42 784.9 775.4 
UE-25 WT #12 29 729.5 728.48 728.33 728.66 729.07 728.61 
USW WT-11 30 730.7 728.46 728.27 728.82 729.21 728.95 
UE-25 J-12 31 727.9 729.01 728.93 728.99 729.38 728.81 
UE-25 JF #3 32 727.8 728.94 728.87 728.92 729.29 728.73 
Cind-R-Lite Well 33 729.8 720.51 719.29 718.22 721.79 721.24 
Ben Bossingham 34 718.4 715.46 715.32 712.73 714.34 712.97 
Fred Cobb 35 702.8 710.47a 710.42a 709.26a 710.03a 709.49a 
Bob Whellock 36 704.1 710.47a 710.42a 709.26a 710.03a 709.49a 
Louise Pereidra 37 705.6 710.5 710.46 709.28 710.06 709.52 
Joe Richards 38 701.7 710.47 710.42 709.26 710.03 709.49 
NDOT Well 39 705.3 713.8 713.67 711.76 713.1 711.87 
James H. Shaw 40 706.7 708.48 708.4 708.56 709.2 708.25 
Airport Well 41 705.5 713.57 713.44 711.61 712.93 711.71 
TW-5 42 725.1 722.08 722.08 722.06 722.08 722.06 
Richard Washburn 43 707.7 705.14 705.05 705.27 705.73 705.14 
Richard Washburn 44 704.4 703.81 703.71 703.78 704.24 703.79 
Nye County 
Develop. Co. 
45 694.4 697.47 697.37 697.38 697.56 697.57 
Fred Wooldridge 46 691.9 699.66 699.38 699.67 699.58 700.65 
Fred J. Keefe 47 694.3 698.53 698.37 698.92 698.75 699.33 
Leslie Nickels 48 694.4 698.07 697.92 698.29 698.27 698.65 
L. Mason 49 722.1 711.55 711.52 711.22 711.47 711.19 
Unknown 50 697.8 697.45 697.36 697.19 697.43 697.38 
Davidson Well 51 690.2 698.36 698.12 698.37 698.3 699.21 
Eugene J. 
Mankinen 
52 707.4 698.22 698.04 698.4 698.3 698.98 
Donald O. Heath 53 698.1 696.51 696.38 696.39 696.62 696.65 
Elvis Kelley 54 691 695.68 695.53 695.68 695.65 696.21 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-64 November 2004 
Table 6-7. Calibration Results: Observed WaterLevel Elevation vs. Calibrated Head for Alternate SZ 
Site-Scale Flow Models AM0, AM1, AM2, AM3, and AM4 (Continued) 
Site Name 
Well 
Number 
Water 
Level 
(m) 
Head 
Model 
AM0 (m) 
Head 
Model 
AM1 (m) 
Head 
Model 
AM2 (m) 
Head 
Model 
AM3 (m) 
Head 
Model 
AM4 (m) 
Manuel Rodela 55 693.6 696.16 696.07 695.72 695.96 695.94 
Charles C. DeFir 
Jr. 
56 706.9 696.46 696.3 696.5 696.45 697 
William R. Monroe 57 699 696.79 696.67 696.86 696.86 697.19 
DeFir Well 58 691.3 695.31 695.15 695.28 695.26 695.82 
Edwin H. Mankinen 59 695.2 695.69 695.61 695.68 695.72 695.88 
Bill Strickland 60 689.2 691.31 691.18 690.84 691.1 691.26 
M. Meese 61 686.4 695.37 695.29 694.84 695.08 695.07 
Theo E. Selbach 62 696.2 695.62 695.54 695.1 695.34 695.33 
C.L. Caldwell 63 691.4 693.58 693.5 693.57 693.56 693.82 
Leonard Siegel 64 709 709.26 709.25 709.18 709.24 709.18 
James K. Pierce 65 690.4 694.4 694.34 694.09 694.24 694.26 
James K. Pierce 66 705.7 694.29 694.23 694.08 694.2 694.2 
Cooks West Well 67 717.2 712.79 712.78 712.71 712.77 712.69 
Cooks East Well 68 718.8 713.53 713.52 713.44 713.5 713.42 
Nye County Land 
Co. 
69 690.1 AWT AWT AWT AWT AWT 
Amargosa Town 
Complex 
70 688.9 693.27 693.24 693.01 693.11 693.11 
Nye County 
Develop. Co. 
71 691.2 697.34 697.34 697.32 697.35 697.33 
Lewis C. Cook 72 717.4 714 713.99 713.95 713.99 713.95 
Lewis C. Cook 73 714.8 714.01 714 713.96 714 713.96 
Amargosa Valley 
Water 
74 701.4 693.28 693.24 693.02 693.12 693.12 
Earl N. Selbach 75 696.5 694.18 694.15 694.15 694.17 694.23 
Lewis N. Dansby 76 694.2 694.96 694.93 694.96 694.97 695.04 
Edwin H. 
Mankinen 
77 694 693.9 693.87 693.8 693.84 693.85 
Willard Johns 78 699.5 705.79 705.79 705.76 705.79 705.76 
USW H-1 tube 1 79 785.5 752.06 752.91 752.79 757.23 753.14 
USW H-1 tube 2 80 736 750.03 750.85 750.9 753.89 751.02 
USW H-1 tube 3 81 730.6 751.41 752.45 751.63 754.44 751.82 
USW H-1 tube 4 82 730.9 752.34 753.51 752.19 755.06 752.47 
USW H-5 upper 83 775.5 772.63 772.7 777.69 780.09 775.16 
USW H-5 lower 84 775.6 772.71 772.76 777.97 780.15 775.23 
UE-25 b #1 lower 85 729.7 730.88 730.95 731.2 732.13 731.12 
UE-25 b #1 upper 86 730.7 730.06 730.12 730.18 731.16 730.21 
USW H-6 upper 87 776 773.26 774.42 775.7 781.52 774.04 
USW H-6 lower 88 775.9 771.99 773.07 774.46 779.96 772.79 
USW H-4 upper 89 730.4 729.77 729.79 729.67 730.69 729.79 
USW H-4 lower 90 730.5 732.58 732.62 733.03 733.89 732.67 
USW H-3 upper 91 731.5 729.57 729.56 729.48 730.44 729.66 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-65 November 2004 
Table 6-7. Calibration Results: Observed WaterLevel Elevation vs. Calibrated Head for Alternate SZ 
Site-Scale Flow Models AM0, AM1, AM2, AM3, and AM4 (Continued) 
Site Name 
Well 
Number 
Water 
Level 
(m) 
Head 
Model 
AM0 (m) 
Head 
Model 
AM1 (m) 
Head 
Model 
AM2 (m) 
Head 
Model 
AM3 (m) 
Head 
Model 
AM4 (m) 
USW H-3 lower 92 755.9 730.61 730.64 730.58 731.6 730.75 
UE-25 p #1 (Lwr 
Intrvl) 
93 752.4 752.26 752.29 752.47 753.31 752.41 
USW 94 731.2 729.77 729.77 729.67 730.62 729.77 
USW SD-7 95 727.6 729.65 729.65 729.58 730.54 729.72 
USW SD-9 96 731.1 743.47 744.3 742.86 744.32 742.28 
USW SD-12 97 730 729.74 729.76 729.64 730.65 729.77 
WT-24 98 839.8 834.14 830.07 834.12 822.91 837.54 
NC-EWDP-1D 99 785.8 793.9 796.43 781.89 797.02 784.43 
NC-EWDP-1S 
probe 1 
100 786.7 794.8 797.03 785.59 797.8 786.29 
NC-EWDP-2D 101 706.3 707.63 707.5 707.4 708.19 707.55 
NC-EWDP-3D 102 717.1 716.77 715.73 714.25 716.51 717.59 
NC-EWDP-3S 
probe 2 
103 718.7 AWT AWT AWT AWT AWT 
NC-EWDP-5SB 104 724.1 717.45 717.38 714.57 716.27 714.78 
NC-EWDP-9SX 
probe 2 
105 766 771.81 774.3 762.84 780.09 763.05 
NC-Washburn-1X 106 714.6 714.96 714.79 712.36 713.94 712.56 
UE-25 J-11 107 732.2 731.52 731.52 731.52 731.52 731.52 
BGMW-11 108 715.9 714.56 714.35 714.3 714.34 715 
Richard Washburn 109 704.1 AWT AWT AWT AWT AWT 
L. Cook 110 713.3 AWT AWT AWT AWT AWT 
Unknown 111 689.5 AWT AWT AWT AWT AWT 
Amargosa Water 112 690.4 AWT AWT AWT AWT AWT 
Lewis C. Cook 113 715.7 AWT AWT AWT AWT AWT 
Unknown 114 690.8 AWT AWT AWT AWT AWT 
USW UZ-N91 115 1186.8 1247.27 1249.4 1222.65 1241.94 1239.23 
NC-EWDP- 
1DX,deep 
120 748.8 789.57 792.09b 779.16 793.01 780.62 
NC-EWDP-1S,P2 121 786.8 794.81 797.03b 785.59 797.8 786.29 
NC-EWDP-2DB 122 713.3 712.63 712.48b 711.81 712.75 712.26 
NC-EWDP-3S,P3 123 719.4 715.83 714.77b 713.35 715.39 716.79 
NC-EWDP-9SX,P1 124 766.7 771.73 774.25b 762.66 780.02 762.93 
NC-EWDP-9SX,P4 125 766.8 771.9 774.37b 763.03 780.17 763.2 
NC-EWDP-4PA 126 717.9 716.08 715.93b 713.08 714.77 713.34 
NC-EWDP-4PB 127 723.6 716.12 715.97b 713.08 714.78 713.35 
NC-EWDP-7S 128 830.1 AWT AWTb AWT AWT AWT 
NC-EWDP-12PA 129 722.9 713.82 712.32b 715.11 712.5 718.64 
NC-EWDP-12PB 130 723 713.82 712.32b 715.11 712.5 718.64 
NC-EWDP-12PC 131 720.7 713.83 712.34b 715.06 712.51 718.62 
NC-EWDP-15P 132 722.5 AWT AWTb AWT AWT AWT 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-66 November 2004 
Table 6-7. Calibration Results: Observed WaterLevel Elevation vs. Calibrated Head for Alternate SZ 
Site-Scale Flow Models AM0, AM1, AM2, AM3, and AM4 (Continued) 
Site Name 
Well 
Number 
Water 
Level 
(m) 
Head 
Model 
AM0 (m) 
Head 
Model 
AM1 (m) 
Head 
Model 
AM2 (m) 
Head 
Model 
AM3 (m) 
Head 
Model 
AM4 (m) 
NC-EWDP-19P 133 707.5 713.64 713.48b 711.58 713.19 712.1 
NC-EWDP-19D 134 712.8 713.87 713.72b 711.89 713.42 712.29 
RSME, m 16c 9.29 9.21 8.56 9.40 8.79 
Output DTNs: LA0409GZ831231.001, LA0409GZ831231.002, LA0409GZ831231.003, LA0409GZ831231.004, 
LA0409GZ831231.005 
NOTE: Entries marked AWT have head measurement higher than the top of the model and are not used in 
calibration. AM = alternate model; RSME = Root Squared Mean Error. 
a Entries are data where the wells are so close together that they are associated with the same FEHM 
computational node. 
b Entries do not use the head data as calibration targets. 
c See Section 6.6.2.1 
Figures 6-18a, 6-18b, and 6-18c show the comparison of simulated heads versus measured 
water-level elevations. The root mean squared error values in residual heads are summarized in 
the last row of Table 6-7 for each alternate model considered to provide a basis for the 
quantitative comparison among them. From the figures and the root mean squared error values it 
can be seen that the alternate flow model calibrations are slightly better than that of the SZ 
site-scale flow model and that the calibration of all the alternate flow models is also similar to 
each other. The improvement in the alternate model root mean squared error is due in part to 
improvements in the model components (HFM, recharge, fluxes, etc.). However, the comparison 
is for illustrative purposes only because the number of wells and weights are not the same 
between the base case and ACM. 
The following observations can be made: 
 The moderate waterlevel targets, those between 740 meters to 780 meters, are much 
better simulated with the alternate flow models than with the SZ site-scale flow model 
 The alternate flow models produced lower head values at WT-6 and G-2, wells 
suspected of being perched, than the SZ site-scale flow model. The SZ site-scale flow 
model prediction was ~100 meters low, while the alternate SZ site-scale flow model 
prediction was ~290 meters low 
 The upward gradient is more accurately replicated with the alternate SZ site-scale flow 
models than with the SZ site-scale flow model. This includes the predictions at UE-25 
p #1 and EWDP-2DB 
 The calibration, in regards to the head data, was relatively independent of the flux 
targets on the sides of the SZ site-scale flow model. In fact, using a single flux target on 
a side proved as effective as using the spatially distributed targets 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-67 November 2004 
Output DTNs: LA0409GZ831231.001, LA0409GZ831231.002. 
NOTE: Symbols represent well locations and their residuals (measured water level  simulated head). The blue crosses represent acceptable values within 
5 meters of the measured heads. The numbers represent well numbers. Well numbers above 115 are new wells that were not used in the SZ site-scale 
flow model calculations. See Table 6-7 for a full list of wells, locations, and head results. This alternative conceptualization is included in 
DTN: LA0409GZ831231.001. 
UTM = Universal Transverse Mercator. 
Figure 6-18a. Residual Heads for Base Case and Alternate Flow Model AM0 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-68 November 2004 
Output DTNS: LA0409GZ831231.001; LA0409GZ831231.002; LA0409GZ831231.003; LA0409GZ831231.004; and LA0409GZ831231.005. 
UTM = Universal Transverse Mercator. 
Figure 6-18b. Residual Heads for Alternate Flow Models AM1 and AM2 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-69 November 2004 
Output DTNs: LA0409GZ831231.004 and LA0409GZ831231.005. 
UTM = Universal Transverse Mercator. 
Figure 6-18c. Residual Heads for Alternate Flow Models AM3 and AM4. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-70 November 2004 
 The flux targets were more accurately matched with the alternate SZ site-scale flow 
model, including AM2, which provided distributed fluxes similar to the SZ site-scale 
flow model 
 The inclusion of additional Nye County targets did not improve either the overall 
calibration or the match at the Nye County wells. 
The flux targets and calibrated fluxes are presented in Section 6.4.6.4. The alternate flow models 
produced a better match between the targets and calibrated values than the SZ site-scale flow 
model. The northernmost value on the western boundary (-271 kg/s) was difficult to match for 
the distributed flux case (AM2). It should be noted that specific discharge estimates (see 
Section 6.4.6.3.7, Table 6-11) are lower for the alternate SZ site-scale flow model. In addition, 
transport analyses (BSC 2004 [DIRS 170036], Appendix E2) indicated that the transport times 
estimated using the alternate SZ site-scale flow model are longer. Therefore, using the SZ 
site-scale flow model for TSPA-LA is conservative and will yield breakthrough curves. 
6.4.6.3.4 Calibration Results: Permeability and Permeability Multipliers 
It can be seen from Table 6-8 that the calibration of the alternate SZ site-scale flow model 
produced similar permeability values to those from the site-scale flow model. The calibrated 
permeability is generally lower in the alternate flow model above the flow path from the 
repository to the compliance boundary. Observations are summarized below. 
 The permeability for the Crater Flat group, Tram, Bullfrog, and Prow Pass, are lower in 
the alternate SZ site-scale flow models than in the SZ site-scale flow model. The spatial 
distribution of these parameters is larger in the alternate SZ site-scale flow model 
 Additional spatially distributed zones for the Crater Flat group produced different 
permeability values for this group near Yucca Mountain. These permeability values 
were lower than those along the flow path in Fortymile Wash. They were approximately 
an order of magnitude smaller near Yucca Mountain than in the Fortymile Wash area 
 The alternate SZ site-scale flow models permeability values for the Solitario canyon 
fault were different from those of the SZ site-scale flow model. The alternate flow 
models permeability values were consistent with Solitario Canyon fault values between 
5  10-15 to 6  10-16 m2 for the most permeable segment of the fault. The SZ site-scale 
flow model permeability value for the Solitario Canyon was 1  10-18 m2 
 With few exceptions discussed below, the calibration was independent of the parameter 
bounds used by PEST. 
Fixed bounds were used for the following parameters: bull (Bullfrog), wa40 (Fortymile Wash), 
bully (Bullfrog near Yucca Mountain), tramy (Tram near Yucca Mountain), prowy (Prow near 
Yucca Mountain), wash (lower Fortymile Wash), and ghos (Ghost Dance fault). The 
permeability depth relationships (i.e., the deeper member of the Crater Flat group have lower 
permeability) were considered when setting the permeability limits for the units. For this reason 
the tramy permeability values were limited to values lower than and up to the bully values. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-71 November 2004 
Likewise, the prowy permeability values were limited to values equal to or higher than the bull 
values. The permeability values for the bully and other parameters listed above did not reach the 
fixed bounds in any of the alternate SZ site-scale flow models. 
The calibrations were relatively insensitive to the Ghost Dance fault parameter. Yet, this 
parameter had a measurable effect on the path lines as discussed further in subsequent sections. 
Table 6-8. Calibration Permeability and Permeability Ranges for the Alternate SZ Site-Scale Flow 
Models 
Name 
Geologic Unit 
or Feature 
Calibrated 
Value 
AM0 (m2) 
Calibrated 
Value AM1 
(m2) 
Calibrated 
Value AM2 
(m2) 
Calibrated 
Value AM3 
(m2) 
Calibrated 
Value AM4 
(m2) P/M 
Minimum 
Value 
(m2) 
Maximum 
Value 
(m2) 
intr (S)Intrusive 
Confining 3.41E-18 3.39E-18 4.03E-18 3.89E-18 4.55E-18 P 1.00E-18 1.00E-10 
gran (S)Granitic 
Confining 5.43E-17 5.38E-17 5.69E-18 4.14E-17 3.69E-17 P 1.00E-18 1.00E-10 
lcla (S)Crystaline 
Confining 3.61E-18 3.57E-18 3.35E-18 4.11E-18 3.96E-18 P 1.00E-19 1.00E-10 
lcar 
(S)Lower 
Carbonate 
Aquifer 2.12E-16 1.94E-16 2.88E-16 5.62E-16 9.94E-16 
P 1.00E-18 1.00E-10 
ucla 
(S)Upper 
Clastic 
Confining 
Unit 8.00E-19 1.08E-19 6.88E-19 2.92E-19 1.18E-18 
P 1.00E-19 1.00E-10 
ucar 
(S)Lower 
Carbonate 
Aquifer 
Thrust 3.47E-15 2.39E-15 3.65E-15 3.86E-15 8.90E-15 
P 1.00E-18 1.00E-10 
lclat 
(S)Lower 
Clastic 
Confining 
Thrust 1.02E-17 9.69E-18 9.21E-18 1.34E-17 1.24E-17 
P 1.00E-18 1.00E-10 
lcart 
(S)Lower 
Carbonate 
Aquifer 
Thrust 1.34E-12 1.05E-12 1.65E-12 1.23E-12 8.44E-13 
P 1.00E-18 5.00E-10 
scon 
(S)Sedimenta 
ry Confining 
Unit 2.03E-15 1.99E-15 1.56E-15 2.13E-15 1.98E-15 
P 1.00E-18 1.00E-10 
vsul 
(S)Lower 
Volcanic and 
Sedimentary 5.05E-19 4.95E-19 4.53E-19 5.30E-19 5.06E-19 
P 1.00E-19 1.00E-10 
ovoa (S)Older 
Volcanic 4.30E-15 3.93E-15 3.63E-15 7.32E-15 1.19E-14 P 1.00E-18 1.00E-10 
belt (S)Belted 
Range 2.33E-14 2.30E-14 2.09E-14 2.46E-14 2.43E-14 P 5.00E-18 1.00E-10 
tram (S)Crater Flat- 
Tram 1.10E-11 1.21E-11 1.22E-11 1.20E-11 8.12E-12 P 1.00E-18 1.00E-10 
bull (S)Crater Flat- 
Bullfrog 9.11E-13 1.00E-12 3.93E-13 1.27E-12 9.73E-13 P 1.00E-12 3.00E-11 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-72 November 2004 
Table 6-8. Calibration Permeability and Permeability Ranges for the Alternate SZ Site-Scale Flow 
Models (Continued) 
Name 
Geologic Unit 
or Feature 
Calibrate 
d Value 
AM0 (m2) 
Calibrated 
Value AM1 
(m2) 
Calibrated 
Value AM2 
(m2) 
Calibrated 
Value AM3 
(m2) 
Calibrated 
Value AM4 
(m2) P/M 
Minimum 
Value 
(m2) 
Maximum 
Value 
(m2) 
prow (S)Crater Flat- 
Prow Pass 0.22 0.19 0.64 0.23 0.38 M 1.00E-05 1.00E+00 
wahm (S)Wahmonie 
Volcanic 1.17E-14 1.16E-14 1.16E-14 1.74E-14 1.70E-14 P 1.00E-18 3.00E-10 
cali (S)Calico Hills 6.99E-17 7.39E-17 7.42E-17 8.89E-17 7.10E-17 P 1.00E-18 1.00E-10 
pain (S)Paintbrush 1.21E-13 1.32E-13 1.04E-13 1.99E-13 3.38E-13 P 1.00E-18 1.00E-10 
timb 
(S)Timber 
Mountain 
Volcanic 4.13E-11 3.57E-11 8.90E-12 2.10E-11 2.10E-11 
P 1.00E-18 5.00E-10 
vose 
(S)Volcanic 
and 
Sedimentary 5.06E-12 4.98E-12 1.62E-11 1.15E-11 1.08E-11 
P 1.00E-18 4.00E-10 
uvoa 
(S)Upper 
Volcanic 
Aquifer 7.96E-16 7.89E-16 7.39E-16 7.92E-16 8.47E-16 
P 5.00E-18 1.00E-10 
lava (S)Lavaflow 
Unit 3.20E-11 3.28E-11 2.44E-11 4.54E-11 4.00E-11 P 1.00E-18 1.00E-10 
lime (S) Limestone 
Aquifer 1.89E-17 1.87E-17 1.73E-17 3.78E-17 4.55E-17 P 1.00E-18 1.00E-10 
oalc 
(S)Older 
Alluvial 
Confining 1.20E-14 1.20E-14 1.08E-14 1.20E-14 1.30E-14 
P 1.00E-18 1.00E-10 
oala (S)Older 
Alluvial Aquifer 4.38E-13 4.42E-13 3.39E-13 6.48E-13 7.62E-13 P 5.00E-18 1.00E-11 
yalc 
(S)Young 
Alluvial 
Confining 5.40E-14 5.37E-14 4.85E-14 5.48E-14 6.05E-14 
P 1.00E-18 1.00E-10 
yala (S)Young 
Alluvial Aquifer 4.94E-13 4.92E-13 4.41E-13 4.51E-13 4.55E-13 P 1.00E-18 1.00E-10 
intrm (N)Intrusive 
Confining 30.4 30.5 34.0 28.5 33.9 1.00E-05 1.00E+04 
granm (N)Granites 1955 1961 198 1481 1430 M 1.00E-05 1.00E+06 
lclam (N)Crystaline 
Confining 69.6 69.2 61.4 57.1 57.3 M 1.00E-05 1.00E+04 
lcarm 
(N)Lower 
Carbonate 
Aquifer 0.21 0.21 0.22 0.19 0.20 
M 1.00E-05 100 
uclam 
(N)Upper 
Clastic 
Confining Unit 0.56 0.56 0.51 0.50 0.52 
M 1.00E-05 100 
ucarm 
(N)Lower 
Carbonate 
Aquifer Thrust 0.97 0.70 1.26 1.11 2.99 
M 1.00E-05 100 
lclatm 
(N)Lower 
Clastic 
Confining 
Thrust 17.4 17.2 16.3 15.4 15.6 
M 1.00E-05 100 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-73 November 2004 
Table 6-8. Calibration Permeability and Permeability Ranges for the Alternate SZ Site-Scale Flow 
Models (Continued) 
Name 
Geologic Unit 
or Feature 
Calibrate 
d Value 
AM0 (m2) 
Calibrated 
Value AM1 
(m2) 
Calibrated 
Value AM2 
(m2) 
Calibrated 
Value AM3 
(m2) 
Calibrated 
Value AM4 
(m2) P/M 
Minimum 
Value 
(m2) 
Maximum 
Value 
(m2) 
lcartm 
(N)Lower 
Carbonate 
Aquifer Thrust 1.97 1.96 1.84 1.74 1.77 
M 1.00E-05 100 
sconm (N)Sedimentary 
Confining Unit 2.76 2.74 2.58 2.45 2.50 M 1.00E-05 100 
vsulm 
(N)Lower 
Volcanic and 
Sedimentary 1.41E-04 1.40E-04 1.33E-04 1.49E-04 1.55E-04 
M 1.00E-05 100 
ovoam (N)Older 
Volcanic 7.65E-04 7.60E-04 7.15E-04 6.51E-04 6.56E-04 M 1.00E-05 100 
beltm (N)Belted 
Range 1.04E-04 1.03E-04 9.70E-05 9.16E-05 9.33E-05 M 1.00E-05 100 
tramm (N)Crater Flat- 
Tram 1.06E-04 7.14E-05 8.55E-04 2.62E-04 4.11E-04 M 1.00E-05 100 
bullm (N)Crater Flat- 
Bullfrog 3.41E-05 3.30E-05 3.01E-05 2.53E-05 1.90E-05 M 1.00E-08 100 
prowm (N)Crater Flat- 
Prow Pass 4.19E-06 4.10E-06 3.98E-06 5.26E-06 5.89E-06 M 1.00E-06 100 
wahm 
m 
(N)Wahmonie 
Volcanic 0.509197 0.495458 0.472581 0.426208 0.449338 M 1.00E-05 100 
calim (N)Calico Hills 10.9 15.3 10.8 20.2 11.4 M 1.00E-05 100 
painm (N)Paintbrush 3.53E-07 3.81E-07 1.54E-07 5.74E-07 6.19E-07 M 1.00E-07 100 
timbm 
(N)Timber 
Mountain 
Volcanic 7.31 7.84 2.93E-03 6.34 5.91 
M 1.00E-05 10000 
vosem 
(N)Volcanic 
and 
Sedimentary 1.26 1.23 1.18 1.01 1.06 
M 1.00E-05 100 
uvoam 
(N) Upper 
Volcanic 
Aquifer 0.76 0.74 0.71 0.66 0.68 
M 1.00E-05 100 
lavam (N) Lavaflow 
Unit 1.03 1.05 0.96 0.90 1.05 M 1.00E-05 100 
limem (N) Limestone 
Aquifer 0.11 0.11 0.11 9.69E-02 9.99E-02 M 1.00E-05 100 
oalcm 
(N) Older 
Alluvial 
Confining 7.65E-02 7.88E-02 7.25E-02 7.85E-02 6.44E-02 
M 1.00E-05 100 
oalam (N) Older 
Alluvial Aquifer 1.97 1.90 1.84 1.99 2.20 M 1.00E-05 100 
yalcm 
(S)Young 
Alluvial 
Confining 3.83 3.76 3.22 2.70 1.38 
M 1.00E-05 100 
yalam (S)Young 
Alluvial Aquifer 1.24 1.20 1.08 1.02 0.66 M 1.00E-05 100 
nsba Solitario Fault 
Component 1 6.00E-15 5.86E-15 4.25E-15 7.97E-15 1.02E-14 P 1.00E-20 1.00E-13 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-74 November 2004 
Table 6-8. Calibration Permeability and Permeability Ranges for the Alternate SZ Site-Scale Flow 
Models (Continued) 
Name 
Geologic Unit 
or Feature 
Calibrate 
d Value 
AM0 (m2) 
Calibrated 
Value AM1 
(m2) 
Calibrated 
Value AM2 
(m2) 
Calibrated 
Value AM3 
(m2) 
Calibrated 
Value AM4 
(m2) P/M 
Minimum 
Value 
(m2) 
Maximum 
Value 
(m2) 
nssb Solitario Fault 
Component 2 9.87E-17 9.97E-17 9.60E-17 9.18E-17 8.41E-17 P 1.00E-20 1.00E-13 
nsym Solitario Fault 
Component 3 6.57E-18 6.67E-18 6.41E-18 5.88E-18 6.61E-18 P 1.00E-18 1.00E-13 
nszm Solitario Fault 
Component 4 7.72E-16 7.23E-16 7.72E-16 1.01E-15 8.61E-16 P 1.00E-18 1.00E-11 
scfs Solitario Fault 
Component 5 3.52E-16 2.84E-16 6.10E-16 5.12E-16 7.42E-16 P 1.00E-18 1.00E-13 
wa40 Forty Mile 
Wash 85.9 93.6 95.4 69.2 75.8 1.00E-05 1.00E+02 
tramy (YM) Crater 
Flat-Tram 200 100 1192 114 267 M 1.00E-5 1.00E+02 
bully (YM)Crater 
Flat-Bullfrog 1.24E-13 1.72E-13 8.07E-14 3.44E-13 4.39E-13 P 1.00E-13 1.00E-10 
prowy (YM)Crater 
Flat-Prow Pass 0.55 0.71 0.26 0.1 0.1 M 1.00E-5 1.00E+02 
intre (E)Intrusive 
Confining 3.31E-17 3.35E-17 2.90E-17 3.16E-17 3.12E-17 P 1.00E-18 1.00E-10 
lcare 
(E)Lower 
Carbonate 
Aquifer 2.53E-15 2.50E-15 2.89E-15 3.30E-15 5.48E-15 
P 1.00E-18 1.00E-10 
lclate 
(E)Lower 
Clastic 
Confining 
Thrust 1.53E-14 1.55E-14 1.34E-14 1.25E-14 1.45E-14 
P 1.00E-18 1.00E-10 
lcarte 
(E)Lower 
Carbonate 
Aquifer Thrust 9.64E-12 1.02E-11 2.85E-12 8.52E-12 8.48E-12 
P 1.00E-18 5.00E-10 
cffz Crater Flat 
Fault 1 3.49E-15 3.72E-15 9.38E-16 8.77E-15 7.96E-15 P 1.00E-17 5.00E-12 
Cff1 Crater Flat 
Fault 2 1.27E-15 1.38E-15 6.86E-16 1.75E-15 2.30E-15 P 1.00E-17 5.00E-11 
Hy95 U.S. Highway 
95 Fault Zone 9.82E-16 6.98E-16 3.01E-15 1.32E-15 5.19E-15 P 1.00E-17 5.00E-11 
wash 
Lower 
Fortymile 
Wash Zone 1.11E-11 1.12E-11 1.41E-11 1.37E-11 1.40E-11 
P 1.00E-11 5.00E-10 
nwtf 
North West 
Trending Fault 
Zone 3.66E-16 3.23E-16 4.99E-16 4.22E-16 6.64E-16 
P 1.00E-16 1.00E-10 
dune Dune Wash 
Fault Zone 5.24E-12 5.34E-12 4.66E-12 5.42E-12 5.73E-12 P 1.00E-12 5.00E-10 
ghos Ghost Dance 
Fault Zone 1.08E-11 1.03E-11 1.17E-11 2.19E-11 2.40E-11 P 1.00E-12 1.00E-11 
Output DTNs: LA0409GZ831231.001; LA0409GZ831231.002; LA0409GZ831231.003; LA0409GZ831231.004; 
LA0409GZ831231.005 
NOTE: (P) = parameter; (M) = multiplier; (N)= northern zone; (S) = southern zone; (E) = eastern zone; 
(YM) =Yucca Mountain zone. If parameter is of type M, table entry is a unit-less multiplier. Values have 
been rounded for consistency of presentation. AM = alternate model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-75 November 2004 
6.4.6.3.5 Calibration Results: Potentiometric Surface and Flow Path Lines 
The results of the calibration are shown in Figure 6-19 through 6-22. These figures were plotted 
using graphical software SURFER for Windows (see Section 3.2). The output from FEHM was 
processed with post-processing code prepare_features_for_surfer V1.0 STN: 11091-1.0-00 
(Los Alamos National Laboratory 2003 [DIRS 171911]). As a result, the coordinates of the 
nodes at the specified elevation/water table, corresponding heads, saturation, temperature, and 
other output parameters were written into a file in the format required by SURFER. These files 
are provided with the corresponding DTNs (see figure footnotes). 
Shown in Figures 6-19 through 6-22 are the potentiometric surface and flow path lines for the 
five alternate SZ site-scale flow models. The similarity between the five alternate SZ site-scale 
flow model outputs is evident. 
Figures 6-19, 6-20, and 6-21 show different particle paths originating from the repository area. 
These paths represent fluid leaving from the southern, central, and northern parts of the 
repository. Figure 6-22 shows the path lines for AM0 through AM4 at elevation 500 meters and 
at the water table. Figure 6-23 through 6-26 show the hydrostratigraphy along the flow paths for 
the SZ site-scale flow model and the alternate models AM0 through AM4. The fluid particles 
travel downward until they reach the Crater Flat Bullfrog unit (colored red). Because of the high 
permeability of the Bullfrog unit, the particles remain in that unit until it ends. Particles leaving 
the northern part of the repository experience a more tortuous transition between the volcanic 
and alluvial aquifers. With the SZ site-scale flow model particles travel in a short transition zone 
consisting of the upper volcanic confining unit until they reach the alluvial part of the flow 
system. This consists of an alluvial uncertainty zone and the lower Fortymile Wash zone. In 
the alternate SZ site-scale flow model, the particles start similarly and travel to the Bullfrog unit. 
However, the top panels of these figures show that the newer rendition of the Bullfrog unit in the 
alternate SZ site-scale flow model is somewhat thinner and more continuous in the north-south 
direction and transitions to the volcanic and sedimentary units (the alluvial aquifer) without 
going through the Calico Hills volcanic unit. Because the Calico Hills unit has a relatively low 
permeability, this could have implications on the flow field. 
The differences along the flow path from the repository can be summarized as follows. The flow 
near the repository area in the alternate SZ site-scale flow model is likely to be very similar to 
that in the SZ site-scale flow model because the HFM changes were small in this portion of the 
model. Flow in the upper Fortymile Wash, in the area also known as the low-gradient area, 
might be expected to change because the character of the Bullfrog unit is different in the two 
HFMs. The alternate SZ site-scale flow model fluid path lines are narrower in width and more 
continuous. Flow in the lower Fortymile Wash is also expected to be somewhat different. The 
changes in the extent of the alluvial aquifer are the major difference. The alluvial uncertainty 
zone included in the SZ site-scale flow model, however, has mitigated some of this difference. 
The flow paths may be impacted by the low permeability of Calico Hills which may prevent the 
flow paths from going more east as in the SZ site-scale flow model thus going in more north 
south direction than the SZ site-scale flow model. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-76 November 2004 
NOTE: Green lines refer to head contours; blue lines refer to the particle paths, and the red lines indicate locations of the Repository and U.S. Highway 95. 
UTM = Universal Transverse Mercator. 
Figure 6-19. Flow Paths from the Repository with Simulated Hydraulic Head Contours for SZ Site-Scale Flow Model and Alternate Flow Model 
AM0 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-77 November 2004 
NOTE: Green lines refer to head contours; blue lines refer to the particle paths, and the red lines indicate locations of the Repository and U.S. Highway 95. 
UTM = Universal Transverse Mercator. 
Figure 6-20. Flow Paths from the Repository with Simulated Hydraulic Head Contours for Alternate Flow Models AM1 and AM2 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-78 November 2004 
NOTE: Green lines refer to head contours; blue lines refer to the particle paths, and the red lines indicate locations of the Repository and U.S. Highway 95. 
UTM = Universal Transverse Mercator. 
Figure 6-21. Flow Paths from the Repository with Simulated Hydraulic Head Contours for Alternate Flow Models AM3 and AM4 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-79 November 2004 
Output DTN: LA034TM831231.002, alternative conceptualizations are included in Output 
DTNs: LA0409GZ831231.001, LA0409GZ831231.002, LA0409GZ831231.003, LA0409GZ831231.004, 
LA0409GZ831231.005. 
NOTE: Green lines refer to head contours at elevation 500 meters; blue dotted lines refer to head contours at the 
water table. Repository outline and U.S. Highway 95, in red, are included for reference. The data used for 
plotting head contours at the water table are located in file sur1002_1002.txt. The data used for plotting 
head contours at the elevation 500 meters are located in file sur1003_1002.txt. Each DTN listed above 
includes both files with these names. 
UTM = Universal Transverse Mercator. 
Figure 6-22. Head Contours, for SZ Site-Scale Flow Model, and Alternate Flow Models AM0, AM1, AM2, 
AM3, and AM4, at Elevation 500 meters and Water Table 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-80 November 2004 
2 ICU 
3 XCU 
4 LCCU 
5 LCA 
6 UCCU 
7 UCA 
8 LCCUT1 
9 LCA T1 
10 SCU 
11 VSULow 
12 OVU 
13 BRU 
14 CFTA 
16 CFPPA 
17 WVU 
18 CHVU 
19 PVA 
20 TMVA 
21 VSU 
22 YVU 
23 LFU 
24 LA 
25 OACU 
26 OAA 
27 YACU 
28 YAA 
15 CFBCU 
AM 0 
N 
E 
HWY 95 
Path 50 Repository 
NOTE: For illustration purposes only. This alternative conceptualization is included in Output DTN: LA0409GZ831231.001. 
UTM = Universal Transverse Mercator. 
Figure 6-23. View of Hydrostratigraphy Along Particle Path 50 for Alternate Flow Model AM0 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-81 November 2004 
Base-case 
N 
E Path 50 
Repository 
HWY 95 
2 Granites 
3 LCCU 
4 LCA 
5 UCCU 
6 LCA-T 
7 UCA 
8 UVF 
12 CF-Tram 
13 CF-Bull 
14 CF-Prow 
15 UVCU 
16 UVA 
17 LFA 
18 LA 
19 VF CU 
20 Alluvium 
11 LVCU 
10 OVA 
9 OVCU 
Output DTN: LA034TM831231.002. 
NOTE: For illustration purposes only. 
UTM = Universal Transverse Mercator. 
Figure 6-24. View of Hydrostratigraphy Along Particle Path 50 for SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-82 November 2004 
Saturated Zone Site-Scale Flow Model 
2 ICU 
3 XCU 
4 LCCU 
5 LCA 
6 UCCU 
7 UCA 
8 LCCUT1 
9 LCA T1 
10 SCU 
11 VSULow 
12 OVU 
13 BRU 
14 CFTA 
16 CFPPA 
17 WVU 
18 CHVU 
19 PVA 
20 TMVA 
21 VSU 
22 YVU 
23 LFU 
24 LA 
25 OACU 
26 OAA 
27 YACU 
28 YAA 
15 CFBCU 
AM 1 
N 
E 
HWY 95 
Path 50 
Repository 
Output DTNs: LA0409GZ831231.002, LA0409GZ831231.003. 
NOTE: For illustration purposes only. 
UTM = Universal Transverse Mercator. 
Figure 6-25. Views of Hydrostratigraphy Along Particle Path 50 for Alternate Flow Models AM1 and AM2 
MDL-NBS-HS-000011 REV 02 6-83 November 2004 
Saturated Zone Site-Scale Flow Model 
3 XCU 
4 LCCU 
5 LCA 
6 UCCU 
7 UCA 
8 LCCUT1 
9 LCA T1 
10 SCU 
11 VSULow 
12 OVU 
13 BRU 
14 CFTA 
16 CFPPA 
17 WVU 
18 CHVU 
19 PVA 
20 TMVA 
21 VSU 
22 YVU 
23 LFU 
24 LA 
25 OACU 
26 OAA 
27 YACU 
28 YAA 
15 CFBCU 
AM 2 
N 
E 
Path 50 
Repository 
HWY 95 
Output DTNs: LA0409GZ831231.002, LA0409GZ831231.003. 
NOTE: For illustration purposes only. These views were created by selecting particle path number 50 from each set of model results. The computational grid 
is sliced along the path and blocks west of the path are removed. Grid blocks above the water table surface are removed. The location of 95 and the 
repository are included for reference and both objects sit at elevation 700 meters. The view is looking south and west with the particle path shown as a 
black ribbon along the vertical face of the grid and originating near the repository outline. The grid elevation has been exaggerated 5x for easier 
viewing. Colors in these images represent the hydrogeologic units as defined by the input HFM and do not include additional zones defined for the 
models. 
UTM = Universal Transverse Mercator. 
Figure 6-25. Views of Hydrostratigraphy Along Particle Path 50 for Alternate Flow Models AM1 and AM2 (Continued) 
MDL-NBS-HS-000011 REV 02 6-84 November 2004 
Saturated Zone Site-Scale Flow Model 
Output DTNs: LA0409GZ831231.004, LA0409GZ831231.005. 
NOTE: UTM = Universal Transverse Mercator. 
Figure 6-26. Views of Hydrostratigraphy along Particle Path 50 for Alternate Flow Models AM3 and AM4 
3 XCU 
4 LCCU 
5 LCA 
6 UCCU 
7 UCA 
8 LCCUT1 
9 LCA T1 
10 SCU 
11 VSULow 
12 OVU 
13 BRU 
14 CFTA 
16 CFPPA 
17 WVU 
18 CHVU 
19 PVA 
20 TMVA 
21 VSU 
22 YVU 
23 LFU 
24 LA 
25 OACU 
26 OAA 
27 YACU 
28 YAA 
15 CFBCU 
AM 3 
Repository 
N 
E 
HWY 95 
Path 50
MDL-NBS-HS-000011 REV 02 6-85 November 2004 
Saturated Zone Site-Scale Flow Model 
3 XCU 
4 LCCU 
5 LCA 
6 UCCU 
7 UCA 
8 LCCUT1 
9 LCA T1 
10 SCU 
11 VSULow 
12 OVU 
13 BRU 
14 CFTA 
16 CFPPA 
17 WVU 
18 CHVU 
19 PVA 
20 TMVA 
21 VSU 
22 YVU 
23 LFU 
24 LA 
25 OACU 
26 OAA 
27 YACU 
28 YAA 
15 CFBCU 
AM 4 
Repository 
N 
E 
HWY 95 
Path 50 
Output DTNs: LA0409GZ831231.004, LA0409GZ831231.005. 
NOTE: These views were created by selecting particle path number 50 from each set of model results. The computational grid is sliced along the path and 
blocks west of the path are removed. Grid blocks above the water table surface are removed. The location of Hwy 95 and the repository are included 
for reference and both objects sit at elevation 700 meters. The view is looking south and west with the particle path shown as a black ribbon along the 
vertical face of the grid and originating near the repository outline. The grid elevation has been exaggerated 5x for easier viewing. Colors in these 
images represent the hydrogeologic units as defined by the input HFM and do not include additional zones defined for the models. 
UTM = Universal Transverse Mercator. 
Figure 6-26. Views of Hydrostratigraphy along Particle Path 50 for Alternate Flow Models AM3 and AM4 (Continued) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-86 November 2004 
6.4.6.3.6 Calibration Results: Sensitivity 
Parameter sensitivity is defined as the ratio of changes in calibration head in response to change 
in a given calibration parameter. Tables 6-9 and 6-10 present calibration sensitivity to the 
calibration parameters used to rank the importance of the parameters to model calibration for the 
alternate flow models. 
Because hydrostratigraphic units are broken into northern and southern groups, there are 
34 model parameters that have sensitivities greater than 0.1. If northern and southern parameters 
are grouped, the 34 model parameters are reduced to 28 parameters with sensitivity greater than 
0.1. 
Table 6-9. Parameter Sensitivity Over All Observation Groups 
Sensitivity over all observation groups 
Parameter Name AM0 AM1 AM2 AM3 AM4 
Intr 5.295E-01 5.569E-01 5.469E-01 5.795E-01 5.892E-01 
Gran 3.477E+00 3.718E+00 4.638E-02 2.030E+00 1.762E+00 
Lcla 1.199E-02 1.850E-02 8.787E-03 7.786E-03 6.125E-03 
Lcar 1.793E-01 1.450E-01 1.369E-01 1.842E-01 2.524E-01 
Ucla 2.018E-01 1.545E+00 2.663E-02 1.197E-02 1.356E-01 
Ucar 1.106E-01 9.434E-02 1.341E-01 1.477E-01 7.343E-01 
Lclat 1.266E-01 1.402E-01 8.945E-02 7.971E-02 4.410E-02 
Lcart 8.223E-01 7.103E-01 7.270E-01 7.438E-01 5.178E-01 
Scon 4.740E-03 6.389E-02 4.505E-03 4.798E-03 4.741E-03 
Vsul 1.689E-01 1.883E-01 1.126E-01 7.515E-02 4.218E-02 
Ovoa 1.540E-01 1.368E-01 1.970E-01 1.957E-01 2.268E-01 
Belt 4.739E-03 4.794E-02 4.505E-03 4.739E-03 4.739E-03 
Tram 1.122E+00 1.167E+00 3.048E+00 1.436E+00 1.264E+00 
Bull 1.043E+00 1.187E+00 5.989E-01 1.091E+00 6.854E-01 
Prow 1.355E-01 2.128E+00 7.830E-02 9.138E-02 9.072E-02 
Wahm 7.067E-03 1.527E-02 9.086E-03 1.036E-02 1.393E-02 
Cali 1.034E+00 1.085E+00 9.608E-01 1.021E+00 1.038E+00 
Pain 3.785E-01 4.427E-01 5.179E-01 5.824E-01 9.589E-01 
Timb 4.006E-01 5.540E-01 1.182E+00 9.980E-01 8.716E-01 
Vose 9.742E-01 1.455E+00 1.032E+00 8.369E-01 7.914E-01 
Uvoa 4.739E-03 5.840E-02 1.303E-01 2.555E-01 4.739E-03 
Lava 2.563E-02 6.683E-02 2.436E-02 3.977E-02 4.367E-02 
Lime 4.746E-03 5.536E-02 4.511E-03 4.744E-03 4.743E-03 
Oalc 4.740E-03 5.535E-02 4.505E-03 4.748E-03 4.741E-03 
Oala 1.516E-02 6.354E-02 1.242E-02 2.160E-02 2.214E-02 
Yalc 4.739E-03 5.350E-02 4.505E-03 4.739E-03 4.739E-03 
Yala 4.741E-03 5.349E-02 4.557E-03 4.740E-03 4.763E-03 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-87 November 2004 
Table 6-9. Parameter Sensitivity Over All Observation Groups (Continued) 
Sensitivity over all observation groups 
Parameter Name AM0 AM1 AM2 AM3 AM4 
Intrm 5.257E-01 5.531E-01 5.421E-01 5.775E-01 5.866E-01 
Granm 3.476E+00 3.706E+00 4.601E-02 2.031E+00 1.762E+00 
Lclam 5.591E-03 4.393E-02 4.585E-03 5.404E-03 5.599E-03 
Lcarm 4.438E-01 4.807E-01 4.334E-01 4.383E-01 4.249E-01 
Uclam 5.042E-03 4.377E-02 4.556E-03 4.790E-03 4.799E-03 
Ucarm 1.105E-01 8.839E-02 1.341E-01 1.476E-01 7.343E-01 
Lclatm 4.739E-03 4.385E-02 4.505E-03 4.739E-03 4.739E-03 
Lcartm 4.739E-03 4.385E-02 4.505E-03 4.739E-03 4.739E-03 
sconm 4.739E-03 4.385E-02 4.505E-03 4.739E-03 4.739E-03 
vsulm 4.739E-03 4.384E-02 4.505E-03 4.739E-03 4.739E-03 
ovoam 4.748E-03 4.376E-02 4.511E-03 4.761E-03 4.799E-03 
beltm 4.739E-03 4.375E-02 4.505E-03 4.739E-03 4.739E-03 
tramm 5.766E-01 4.316E-01 4.070E+00 1.191E+00 1.214E+00 
bullm 7.952E-03 5.119E-02 5.864E-03 6.073E-03 5.286E-03 
prowm 4.827E-03 8.917E-02 4.510E-03 4.790E-03 4.809E-03 
wahmm 4.739E-03 7.661E-02 4.505E-03 4.739E-03 4.739E-03 
calim 2.976E-01 4.395E-01 3.862E-01 6.668E-01 3.824E-01 
painm 8.235E-03 2.144E-01 7.227E-03 4.936E-03 5.551E-03 
timbm 8.233E-02 2.000E-01 5.713E-01 2.539E-02 6.395E-03 
vosem 3.776E-02 4.994E-02 4.505E-03 6.791E-02 3.590E-01 
uvoam 6.078E-02 4.993E-02 4.505E-03 1.313E-02 2.072E-01 
lavam 6.543E-02 6.627E-02 4.505E-03 2.976E-02 1.083E-02 
limem 5.607E-02 5.821E-02 4.505E-03 5.468E-03 3.181E-02 
oalcm 1.522E-02 9.416E-02 4.505E-03 2.632E-02 7.004E-03 
oalam 6.104E-03 5.219E-02 4.505E-03 5.839E-03 4.819E-03 
yalcm 5.667E-02 5.617E-02 4.505E-03 6.805E-03 3.884E-02 
yalam 3.719E-02 5.139E-02 4.505E-03 1.509E-02 4.619E-02 
nsba 7.034E-01 7.678E-01 5.950E-01 7.227E-01 7.034E-01 
nssb 1.277E-02 4.966E-02 6.119E-03 2.024E-02 4.873E-03 
nsym 4.853E-03 4.908E-02 4.576E-03 4.825E-03 4.786E-03 
nszm 7.614E-01 4.069E-01 8.646E-01 5.332E-01 1.991E-01 
scfs 1.688E-01 2.413E-01 2.124E-01 1.802E-01 1.820E-01 
wa40 5.422E-01 5.989E-01 5.778E-01 6.215E-01 6.339E-01 
tramy 1.680E-01 2.521E-01 8.637E-02 2.124E-01 9.845E-02 
bully 3.450E-01 7.163E-01 3.643E-01 4.572E-01 9.565E-02 
prowy 8.589E-02 1.568E-01 4.802E-02 6.939E-02 5.122E-02 
Intre 5.837E-03 1.094E-01 5.107E-03 5.121E-03 4.927E-03 
lcare 2.869E-01 3.151E-01 2.787E-01 3.962E-01 3.578E-01 
lclate 1.230E-02 1.070E-01 1.372E-02 2.062E-02 2.569E-02 
lcarte 8.464E-02 1.094E-01 1.342E-01 7.147E-02 4.148E-02 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-88 November 2004 
Table 6-9. Parameter Sensitivity Over All Observation Groups (Continued) 
Sensitivity over all observation groups 
Parameter Name AM0 AM1 AM2 AM3 AM4 
Cffz 8.493E-01 9.063E-01 1.163E-01 9.740E-01 6.927E-01 
cff1 1.510E+00 1.628E+00 7.122E-01 1.234E+00 1.531E+00 
hy95 5.468E-01 4.817E-01 1.280E+00 5.979E-01 9.705E-01 
wash 1.651E+00 1.825E+00 1.691E+00 1.862E+00 1.865E+00 
nwtf 7.590E-02 1.045E-01 4.944E-02 6.217E-02 4.962E-02 
dune 5.176E-03 7.213E-02 4.687E-03 4.967E-03 5.714E-03 
ghos 1.248E-02 7.410E-02 6.323E-03 1.910E-02 6.737E-03 
Intr 1.715E-01 3.864E-02 2.413E-01 1.096E-01 1.558E-01 
Gran 6.772E-02 1.640E+00 1.394E-01 1.179E-01 3.272E-02 
Lcla 9.092E-02 1.385E-01 2.038E-03 2.466E-03 1.685E-02 
Lcar 3.586E-01 2.302E-01 2.555E-01 2.461E-01 1.444E-01 
Ucla 8.955E-02 1.295E-01 2.090E-02 7.396E-03 6.732E-02 
Ucar 9.454E-02 1.150E-01 4.015E-04 5.933E-04 7.011E-02 
Lclat 1.593E-01 1.070E-01 5.210E-03 3.371E-03 7.300E-02 
Lcart 1.201E+00 1.067E+00 1.425E+00 6.986E-01 5.394E-02 
Scon 1.277E-02 1.538E-01 5.334E-01 1.100E-03 5.464E-02 
Vsul 3.412E-01 1.277E-01 5.723E-02 7.174E-03 5.330E-02 
Ovoa 5.438E-01 8.890E-01 6.380E-01 8.701E-01 1.031E+00 
Belt 1.677E-01 1.574E-01 6.918E-05 1.033E-05 5.380E-02 
Tram 5.883E+00 1.238E+01 7.835E+00 5.106E+00 4.839E+00 
Bull 1.559E+00 1.971E+00 6.223E+00 7.125E-01 1.906E+00 
Prow 9.502E-01 4.720E-01 6.777E-01 5.857E-01 4.860E-01 
wahm 3.148E-01 3.979E-01 3.657E-02 4.039E-02 3.470E-01 
Cali 1.206E+00 2.316E+00 2.247E+00 4.023E+00 3.999E+00 
Pain 1.097E+00 2.468E+00 1.528E+00 1.302E+00 1.233E+00 
Timb 1.039E+00 2.495E+00 7.026E-01 2.373E-01 1.859E+00 
Vose 4.628E+00 1.830E+01 3.512E+00 4.661E+00 6.033E+00 
Uvoa 2.444E-01 3.331E-02 1.299E-04 3.156E-05 6.024E-02 
Lava 3.191E-01 3.797E-02 8.208E-02 1.134E-01 1.190E-01 
Lime 3.104E-01 3.502E-02 7.532E-05 1.309E-04 1.221E-01 
Oalc 3.104E-01 3.508E-02 3.655E-04 1.043E-03 1.223E-01 
Oala 3.075E-01 6.581E-01 2.552E-03 5.403E-03 1.343E-01 
Yalc 3.025E-01 1.249E-01 2.144E-04 1.571E-04 1.435E-01 
Yala 3.024E-01 1.243E-01 2.385E-05 3.135E-05 1.436E-01 
Intrm 1.963E-01 1.186E-01 2.562E-01 1.349E-01 9.985E-02 
granm 2.147E-01 1.615E+00 1.292E-01 1.160E-01 4.193E-02 
Lclam 2.203E-01 2.632E-01 3.910E-04 3.039E-04 9.866E-02 
lcarm 1.863E-01 2.348E-01 5.866E-02 3.744E-02 1.097E-01 
uclam 2.249E-01 1.886E-01 1.187E-04 1.272E-04 8.425E-02 
ucarm 2.293E-01 1.649E-01 3.097E-04 3.263E-04 7.883E-02 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-89 November 2004 
Table 6-9. Parameter Sensitivity Over All Observation Groups (Continued) 
Sensitivity over all observation groups 
Parameter Name AM0 AM1 AM2 AM3 AM4 
lclatm 2.329E-01 1.516E-01 1.611E-05 1.110E-05 7.386E-02 
lcartm 2.329E-01 1.509E-01 4.041E-05 1.319E-05 7.377E-02 
sconm 2.330E-01 1.502E-01 1.146E-04 1.994E-05 7.350E-02 
vsulm 2.331E-01 1.496E-01 2.911E-05 1.863E-05 7.336E-02 
ovoam 2.342E-01 1.441E-01 3.465E-03 1.830E-04 7.148E-02 
beltm 2.349E-01 1.390E-01 6.656E-06 3.694E-06 6.966E-02 
tramm 1.586E+00 2.321E-01 1.159E+01 3.148E+00 4.288E+00 
bullm 1.820E-01 2.154E-01 2.918E-03 5.622E-03 2.661E-01 
prowm 1.819E-01 2.016E-01 2.209E-04 6.004E-04 4.220E-02 
wahmm 1.824E-01 1.913E-01 1.101E-06 3.821E-06 3.834E-02 
calim 1.084E+00 1.864E+00 1.999E+00 3.870E+00 3.784E+00 
painm 5.414E-01 1.878E-01 4.688E-02 2.374E-02 1.604E-01 
timbm 4.767E-01 1.354E-01 3.954E-01 4.029E-01 1.561E-01 
vosem 4.718E-01 1.346E-01 3.680E-05 4.942E-05 1.409E-01 
uvoam 4.711E-01 1.341E-01 1.429E-04 5.285E-05 1.408E-01 
lavam 4.707E-01 1.335E-01 2.125E-04 3.153E-05 1.407E-01 
limem 4.703E-01 1.331E-01 4.692E-04 6.032E-04 1.406E-01 
oalcm 4.623E-01 1.326E-01 1.081E-04 2.021E-04 1.390E-01 
oalam 4.620E-01 1.318E-01 1.815E-04 1.595E-03 1.389E-01 
yalcm 4.592E-01 1.314E-01 4.657E-04 6.248E-05 1.376E-01 
yalam 4.587E-01 1.307E-01 7.668E-05 8.647E-05 1.375E-01 
nsba 3.035E+00 2.331E-01 2.214E+00 1.931E+00 2.332E+00 
nssb 5.162E-01 1.101E-01 4.438E-02 1.435E-02 9.249E-02 
nsym 2.256E-01 1.063E-01 6.594E-02 2.137E-02 9.386E-02 
nszm 5.617E-01 1.005E-01 1.774E+00 8.866E-01 4.426E-01 
scfs 3.450E-01 3.637E-01 3.786E-01 4.396E-01 2.660E-01 
Wa40 4.836E-01 1.540E+00 5.721E+00 4.564E-01 4.409E-01 
tramy 1.710E+00 8.188E-01 5.722E+00 1.113E+00 6.546E-01 
bully 3.558E+00 9.273E-01 1.731E+00 1.306E+00 1.701E+00 
prowy 8.141E-01 2.201E-01 6.336E+00 2.011E-01 1.714E+00 
intre 2.867E-01 4.121E-02 3.128E-03 3.742E-03 2.843E-01 
lcare 2.956E-01 4.289E-02 6.589E-03 6.968E-03 2.790E-01 
lclate 2.917E-01 4.255E-02 2.714E-03 1.178E-02 2.715E-01 
lcarte 5.963E-01 5.685E-02 1.046E+00 5.986E-01 1.596E-01 
cffz 7.380E-01 1.369E+00 3.021E-01 1.272E+00 1.216E+00 
Cff1 2.465E+00 2.221E+01 2.070E+00 3.084E+00 4.195E+00 
hy95 1.693E+00 1.954E+00 3.844E-01 5.661E-01 1.568E+00 
wash 1.241E+01 1.075E+00 1.228E+01 1.322E+01 1.591E+01 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-90 November 2004 
Table 6-9. Parameter Sensitivity Over All Observation Groups (Continued) 
Sensitivity over all observation groups 
Parameter Name AM0 AM1 AM2 AM3 AM4 
nwtf 2.143E-01 9.561E-02 6.586E-02 6.843E-02 1.522E-01 
dune 1.883E-01 9.673E-02 3.708E-02 1.534E-02 1.235E-01 
ghos 2.532E-01 2.028E-01 5.929E+00 1.045E-01 1.243E-01 
Output DTNs: LA0409GZ831231.001, LA0409GZ831231.002, LA0409GZ831231.003, 
LA0409GZ831231.004, LA0409GZ831231.005 
AM = alternate model 
Table 6-10. Parameter Sensitivity Over Observation Group Path 
Sensitivity over observation group PATH 
Parameter Name AM0 AM1 AM2 AM3 AM4 
Lcart 1.201E+00 1.067E+00 1.425E+00 6.986E-01 5.394E-02 
Tram 5.883E+00 1.238E+01 7.835E+00 5.106E+00 4.839E+00 
Prow 9.502E-01 4.720E-01 6.777E-01 5.857E-01 4.860E-01 
Cali 1.206E+00 2.316E+00 2.247E+00 4.023E+00 3.999E+00 
Pain 1.097E+00 2.468E+00 1.528E+00 1.302E+00 1.233E+00 
Timb 1.039E+00 2.495E+00 7.026E-01 2.373E-01 1.859E+00 
Vose 4.628E+00 1.830E+01 3.512E+00 4.661E+00 6.033E+00 
tramm 1.586E+00 2.321E-01 1.159E+01 3.148E+00 4.288E+00 
calim 1.084E+00 1.864E+00 1.999E+00 3.870E+00 3.784E+00 
nsba 3.035E+00 2.331E-01 2.214E+00 1.931E+00 2.332E+00 
tramy 1.710E+00 8.188E-01 5.722E+00 1.113E+00 6.546E-01 
bully 3.558E+00 9.273E-01 1.731E+00 1.306E+00 1.701E+00 
Cff1 2.465E+00 2.221E+01 2.070E+00 3.084E+00 4.195E+00 
hy95 1.693E+00 1.954E+00 3.844E-01 5.661E-01 1.568E+00 
wash 1.241E+01 1.075E+00 1.228E+01 1.322E+01 1.591E+01 
Output DTNs: LA0409GZ831231.001, LA0409GZ831231.002, LA0409GZ831231.003, LA0409GZ831231.004, 
LA0409GZ831231.005. 
AM = alternate model 
The following observations can be made of the parameter sensitivity analysis: 
 The most important parameters for the overall calibration were the permeabilities of 
gran, tram, prow, cali, vose, granm, cff1, hy95, and wash. The gran and granm are the 
granite units and are important to the estimation of the boundary flux targets. The 
parameter vose refers to the shallow volcanic and sedimentary unit that was not 
represented in the SZ site-scale flow model. The cff1 is a segment of the crater flat fault 
and is important in matching the flux boundary conditions on the west side. 
 It is noted that the potentiometric surfaces for all alternative conceptual models AM0 
through AM4 indicate limited mound in scattered areas along Fortymile Wash 
(Figures 6-19 to 6-21). The mounds are the results of recharge along Fortymile Wash. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-91 November 2004 
The figures indicate that the mounds dissipate downward as shown by the potentiometric 
surface at the 500-meter elevation. There are no observation wells along Fortymile 
Wash to confirm or refute the existence of the mounds. The mounds are localized, are 
small in areal extent, and do not appear to impact the flow paths from the water table 
below the repository to the accessible environment. There is no sinks in the 
potentiometric surface. 
 The most important parameters for calibration along the flow path were lcart, tram, 
prow, cali, pain, timb, vose, tramm, calim, nsba, tramy, bully, cff1, hy95, and wash. The 
observations along the flow path have different sensitivities than the overall sensitivities. 
The sensitivities include more parameters that are near Yucca Mountain. In particular, 
there are now sensitivities to nsba, a portion of the Solitario Canyon fault. 
The sensitivity of parameter along the flow path is studied because of the importance of 
calibration along the flow path to predicted particle path lines. 
6.4.6.3.7 Calibration Results: Specific Discharge 
The calibrated specific discharge for the SZ site-scale flow model and alternate flow models 
results are presented in Table 6-11. Specific discharge is computed by calculating the transport 
time of the 50th particle of 100 particles, all released at the same time, to cross the 18-kilometer 
compliance boundary. The velocity does not account for any tortuosity in the particle path and is 
computed as the 18-kilometer distance divided by transport time. The alternate SZ site-scale 
flow models (AM0-AM4) produce specific discharge values in the range of 0.459 to 0.653 m/yr 
compared to the SZ site-scale flow model specific discharge of 1.3 m/yr at the 18-kilometer 
boundary. The reasons for the difference are that the calibrated permeabilities values for some of 
the units that dominate the flow paths are lower in the alternate SZ site-scale flow models. 
Table 6-11. Specific Discharge 
SZ Site-Scale Flow model AM0 AM1 AM2 AM3 AM4 
1.317 0.51 m/yr 0.459 m/yr 0.630 m/yr 0.591 m/yr 0.653 m/yr 
Output DTNs: LA0409GZ831231.001, LA0409GZ831231.002, LA0409GZ831231.003, 
LA0409GZ831231.004, LA0409GZ831231.005. 
AM  alternate model; SZ = saturated zone. 
6.4.6.3.8 Calibration Results: Flux Uncertainty 
Groundwater flow fields are the major output of the SZ site-scale flow model. These flow fields 
are used in transport calculations that support TSPA. Quantification of uncertainty in 
groundwater flux is thus very important. The flux through the model has a local and regional 
component. The local component results from recharge near Yucca Mountain and the regional 
component results from flux entering the model boundaries. These boundary fluxes are obtained 
from the 2001 DVRFS as described previously. Even though the local recharge is only about 
10 percent of the total flux leaving the models southern boundary, it is important to flow paths 
originating in the repository area. In this section, the impact of uncertainty in the boundary 
fluxes on the flow paths is investigated. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-92 November 2004 
The five different scenarios represented by the alternate SZ site-scale flow model runs can be 
used to evaluate the effect of flux uncertainty on groundwater flow field specific discharge and 
flow paths. Using the change in flux targets derived from 2001 DVRFS as a surrogate of flux 
uncertainty, it is noted (Table 6-12) that the flux flowing into the north boundary of the site scale 
model changed about 30 percent. The flux flowing into the west boundary changed about 
220 percent and actually reversed directions. The flux flowing into the east north boundary was 
not changed between the different alternate SZ site-scale flow models. 
The east side used a smaller flux target in AM3 than AM0. This was done because the HFM-27 
did not incorporate a highly permeable thrust zone in the southeast corner of the model that was 
present in the SZ site-scale flow model and the 1997 DVRFS. This high flow entered and left in 
the extreme southeast corner and effectively doubled the flow through the southern boundary. 
The discussion of the calibration results noted the following: 
 The various combinations of fluxes are matched well with the alternate flow models 
 The degree of calibration is similar for all the alternate flow models 
 The flow paths are equivalent for all the alternate SZ site-scale flow models 
 The parameter estimates were similar for all the alternate SZ site-scale flow models 
 It is concluded, at least for the particle paths and flow field, that the alternate site-scale 
model is insensitive to the uncertainty in the boundary fluxes derived from the 2001 
DVRFS. 
Some important path line sensitivities were discovered during the analysis of the alternate 
models. The most important was the Ghost Dance fault parameter ghos. This was the only 
bounded parameter in all the alternate models. The presented results use a bounded ghos of 
1  10-12 m2. By bounding this parameter at 1  10-11 m2, the flow path changes. The 
comparison of flow paths is shown in Figures 6-19 to 6-21 
6.4.6.4 Comparison of Boundary Target Fluxes 
A comparison of target fluxes and the fluxes derived from the SZ site-scale flow model and 
alternate flow models are presented in Table 6-12. As indicated in Table 6-12, the SZ site-scale 
flow model compared well to the 1997 regional flow model target boundary fluxes when 
integrated on each boundary. The exception was the west boundary where the fluxes were not 
used as targets, because differences in hydrostratigraphy between the SZ site-scale flow model 
and the 1997 DVRFS model (DAgnese et al. 1997 [DIRS 100131]) would not allow meaningful 
comparison. A similar match between target and calibrated flux values in the alternate flow 
model has been achieved. 

MDL-NBS-HS-000011 REV 02 6-93 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-12. Calibration Results: Comparison of Flux Target with Flux Calibrated Values 
AM0 Flux (kg/s) AM1 Flux (kg/s) AM2 Flux (kg/s) AM3 Flux (kg/s) AM4 Flux (kg/s) 
Base-Case Flux 
(kg/s) 
Target Calibrate Target Calibrate T a r g e t Calibrate Target Calibrate Target Calibrate Target Calibrate 
213.30 
.05197 
(-213.248) 
-.081 
-15.08 
(-14.999) 
-56.10 
-48.87 
(7.23) 
-1.26 
-12.35 
(-11.09) 
West 
125.00 
-120.89 
(4.11) 
125.00 
99.05 
(-25.96) 
-28.10 
-4.055 
(24.045) 
-119.00 
-57.06 
(61.94) 
-119.00 
-112.84 
(6.16) 
-118.7* 
-2.69 
(116.02) 
-71.32 
-61.86 
(9.46) 
-0.023 
-13.696 
(-13.673) 
-147.67 
-148.51 
(-0.84) 
0.120 
0.154 
(0.034) 
East 
-209.0 
0 
-207.77 
(1.23) 
-209.00 
-211.10 
(-2.10) 
-1.53 
10.31 
(11.84) 
-209.00 
-189.52 
(19.48) 
-96.00 
-89.70 
(6.30) 
-561.3 
-513.68 
(47.65) 
MDL-NBS-HS-000011 REV 02 6-94 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-12. Calibration Results: Comparison of Flux Target with Flux Calibrated Values (Continued) 
-217.67 
-208.04 
(9.63) 
-56.57 
-44.24 
(12.33) 
6.91 
19.09 
(12.18) 
North 
-271.00 
-283.43 
(-12.43) 
-271.00 
-272.23 
(-1.23) 
-1.32 
4.25 
(5.57) 
-271.00 
-274.28 
(-3.28) 
-271.00 
-284.37 
(-13.37) 
-195.8 
-168.8 
(26.99) 
South 
403.6 
419.37 
(5.77) 
403.6 
433.20 
(29.60) 
410.51 
572.05 
(161.536) 
648.2 
570.59 
(-77.61) 
535.2 
535.82 
(0.62) 
789.6* 
733.75 
(-55.85) 
DTN: SN9908T0581999.001 [DIRS 132867]  base case model target fluxes, file 02_calib.pest. 
DTN: LA0409GZ831231.001; LA0409GZ831231.002; LA0409GZ831231.003; LA0409GZ831231.004; LA0409GZ831231.005  alternate model calibrated 
fluxesLA0304TM831231.002  base case model calibrated fluxes, files named sz_site_2004.pest. 
NOTE: Location of AM2 distributed fluxes are given in Table 6-11. 
South boundary flux is not a calibration target in the alternate models. It is calculated as the negative of the sum of west, east and north boundary fluxes 
and infiltration flux. 
*These fluxes (west and south) were not used as targets in SZ site-scale flow model calibration. The sum of the target boundary fluxes and infiltration flux 
is not zero (BSC 2004 [DIRS 170015], Section 6.5.1). 
Numbers in the parentheses are residuals between the corresponding target fluxes and calibrated fluxes. 
AM = alternate model 
AM0 Flux (kg/s) AM1 Flux (kg/s) AM2 Flux (kg/s) AM3 Flux (kg/s) AM4 Flux (kg/s) 
Base-Case Flux 
(kg/s) 
Target Calibrate Target Calibrate T a r g e t Calibrate Target Calibrate Target Calibrate Target Calibrate 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-95 November 2004 
6.4.6.5 Conclusions from Alternate Flow Models 
Based on the updated and improved HFM-27, more consistent flux targets from the 2001 
DVRFS model, and additional waterlevel calibration targets from the Nye County drilling 
program, the alternate model (AM0, AM1, AM2, AM3, AM4) provide similar representations of 
the SZ flow system near Yucca Mountain. Results indicate that the important parameters in the 
SZ site-scale flow model are again the most sensitive parameters in the alternate SZ site-scale 
flow model. Probable flow paths, considering the differences between HFM-19 and HFM-27, 
are similar in both models. The following conclusions are noted: 
 Alternate SZ site-scale flow models result in hydraulic heads generally consistent with 
the SZ site-scale flow model. Parameter values are consistent in the alternative models 
and fall within the range of measured data where available. 
 Specific discharge values are lower (0.459-0.653 m/yr) in the alternate SZ site-scale 
flow models than in the SZ site-scale flow model (1.3 m/yr). 
 Particle paths are more north/south with less east/west deviation in the alternate SZ 
site-scale flow models than in the SZ site-scale flow model and thus shorter between the 
repository and the 18-kilometer compliance boundary. 
 Particle paths are insensitive to range of boundary fluxes used. Thus, the large 
uncertainty of fluxes derived from the 2001 DVRFS has little impact on the site-scale 
flow model predictions. 
6.4.7 Summary of the Alternative Conceptual Models 
Table 6-13 summarizes the ACMs considered and their screening status. Compared to the SZ 
site-scale flow model, the alternate mode produces lower seepage velocity that will result in 
slower transport and therefore larger transport times. On the other hand, the alternate flow 
model predicts shorter flow paths that may result in faster transport and therefore smaller 
transport times. The combined effects were investigated in the transport simulations (BSC 2004 
[DIRS 170036]) which shows that transport time predicted by the alternate model are larger than 
the SZ site-scale flow model and therefore that using the SZ site-scale flow model yields 
conservative results for TSPA-LA. Based on this result the SZ site-scale flow model discussed 
in this model report was determined to be an appropriate and conservative model for use in 
TSPA-LA calculations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-96 November 2004 
Table 6-13. Alternative Conceptual Models Considered 
Alternative 
Conceptual Model Key Assumptions 
Screening Assessment and 
Basis 
Uncertainty 
Propagation Forward 
Large hydraulic 
gradient 
The large hydraulic gradient is a 
result of perched water or a 
result of low permeability or 
large head 
Different conceptualizations of 
a LHG do not result in 
different flow field or specific 
discharge results. This is 
based on analysis of the 
various conceptualizations of 
the LHG 
This is not necessary 
to propagate forward 
Solitario Canyon Solitario Canyon goes deep into 
the carbonate aquifer or it only 
goes to the top of the carbonate 
aquifer 
Different conceptualizations of 
the role of Solitario Canyon 
do not result in different flow 
field or specific discharge 
results. This is based on 
computer analysis and 
simulation of the 
representation of Solitario 
Canyon. See Section 6.7.2.1 
This is not necessary 
to propagate forward 
Vertical anisotropy Vary the range of the vertical to 
horizontal permeability 
The range of vertical to 
horizontal permeability affects 
the flow field and the specific 
discharge 
This is not necessary 
to propagate forward 
Horizontal 
anisotropy 
Vary the range of the horizontal 
maximum to horizontal minimum 
permeability 
The range of horizontal 
maximum to horizontal 
minimum permeability does 
not significantly affect the flow 
field and the specific 
discharge 
This uncertainty needs 
to be propagated in the 
generation of 
breakthrough curves 
Potentiometric 
surface 
Different potentiometric 
interpretations of water-level 
data 
Compare model predictions of 
potentiometric surface to the 
different interpretations. The 
different interpretations do not 
affect the flow field or specific 
discharge results 
This is not necessary 
to propagate forward 
Water table rise 
due to future 
climates 
Future climates can change 
water table levels 
Compare model predictions of 
using different water table 
levels. The different 
interpretations do not affect 
the flow-field spatial 
distribution (only the 
magnitude) 
This is not necessary 
to propagate forward. 
Specific discharge 
calculations involve 
only the scaling of 
site-scale flow model 
results 
Alternate SZ 
site-scale flow 
models 
Reinterpreted HFM, boundary 
fluxes and recharge from the 
2002 regional model and 2004 
UZ model, and additional Nye 
County water-level data 
Specific discharge smaller 
than that of the SZ site-scale 
flow model. However the flow 
paths are North-South and 
may be shorter than those in 
the SZ site-scale flow model 
The uncertainty which 
results in shorter flow 
paths needs to be 
evaluated in transport 
simulations 
HFM = hydrogeologic framework model; LHG = large hydraulic gradient; SZ = saturated zone; 
UZ = unsaturated zone. 

SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-97 November 2004 
6.5 MODEL FORMULATION OF CONCEPTUAL MODEL 
6.5.1 Mathematical Description of Conceptual Model 
An effective continuum approach is adopted for simulating groundwater flow through the 
fractured rock and alluvial materials within the domain of the SZ site-scale flow model. Based 
on this conceptualization, the equations governing groundwater flow can be derived by 
combining the equations describing the conservation of fluid mass and Darcys Law (Freeze and 
Cherry 1979 [DIRS 101173], Section 2.11). The equations presented below are for an isotropic, 
isothermal medium. The conservation of fluid mass is: 
, 0 = +  . + 
. 
. 
mass mass 
mass q f 
t 
A 
(Eq. 6-1) 
where 
. is first derivative, 
mass A is the fluid mass per unit volume given by: 
,l mass A f. = (Eq. 6-2) 
mass f is the fluid mass flux given by: 
, v f l mass . = (Eq. 6-3) 
f is the porosity in the system (dimensionless), 
l . is the fluid density (kg/m3), 
v is the fluid velocity (m/s), 
mass q is the fluid mass source (kg/s). 
The velocity of the fluid can be expressed by Darcys Law: 
), ( g P k v l .
 
- . - = (Eq. 6-4) 
where 
 is the dynamic viscosity of the fluid (kg/m/s), 
P is the fluid pressure (Pa), 
k is the permeability (m2), 
g is the acceleration resulting from gravity (m2/s). 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-98 November 2004 
Equations 6-1 and 6-4 can be combined to yield: 
, 0 = 
. 
. 
+ 
.
. 
+ + 
. 
 . - 
t 
A 
D 
z 
q P D mass 
l mass m 
g 
mass . (Eq. 6-5) 
where 
Dmass is hydraulic conductivity. 
Equation 6-5 is the fundamental equation describing groundwater flow. Here z is oriented in the 
direction of gravity and the hydraulic conductivity is given by: 
 
.g k D l 
mass = . 
Groundwater flow is simulated in the SZ site-scale flow model by obtaining a numerical solution 
to this equation. Solution of this equation requires the specification of the pressure at the 
boundaries of the solution domain. For steady-state calculations, solution of this equation does 
not require specification of initial conditions (initial pressure distribution throughout the solution 
domain), because Equation 6-5 (at very large times) represents steady-state flow, which is 
independent of initial conditions. 
Conservation of fluid-rock energy is expressed by the equation: 
, 0 = +  . + 
. 
. 
e e 
e q f 
t 
A (Eq. 6-6) 
where the energy per unit volume, e A , is given by: 
l l r r e u u A f. . f + - = ) 1 ( , (Eq. 6-7) 
with T c u pr r = , and the energy flux, e f , is given by: 
T K v h f l l e . - = . . (Eq. 6-8) 
Here, 
the subscript r refers to the rock matrix, 
the subscript l refers to the liquid, 
the subscript e refers to energy, 
r u and l u are specific internal energies, 
pr c is the specific heat, 
l h is specific enthalpy, 
K is an effective thermal conductivity, 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-99 November 2004 
T is the temperature, and 
e q is the energy contribution from sources and sinks. 
Equations (6-6) and (6-4) can be combined to yield: 
0 ) ( / ) ( = 
. 
. 
+ 
.
. 
+ + .  . - .  . - 
t 
A 
D 
z 
q T K P D e 
l e e g e . , (Eq. 6-9) 
where the transmissivity term is given by; 
.mass l e D h D = (Eq. 6-10) 
It is assumed that a steady-state model is sufficient for calibration purposes and the intended use 
of the SZ site-scale flow model. There are two potential causes of transient flow that are relevant 
to this assumption: (1) changes in climate over the past 15,000 years, and (2) pumping from 
wells south of the model domain during approximately the last 40 years. Use of the steady-state 
assumption requires that the modern-day flow system has had sufficient time to completely 
equilibrate to both of these perturbations to the natural system. It is noted that transient tests 
(C-wells and Alluvial Testing Complex) were performed and that derived permeability values 
from those tests were considered in the validation of the numerical model. It is not expected that 
the model can reproduce the transient tests, largely due to the 500-m gridblocks. Because 
transient pumping is not used in any Yucca Mountain radionuclide migration simulations and 
steady-state gradients are modeled accurately with the model, this does not invalidate the 
steady-state assumption. Climate change and other transient impacts are incorporated in the SZ 
flow and transport abstractions (BSC 2004 [DIRS 170042], Section 6.5) 
The conceptual model of the long-term groundwater flow in this region holds that recharge rates 
and, consequently, the elevation of the water table and groundwater flow rates were larger during 
the last glacial pluvial period. The time required for the flow system to equilibrate to a more arid 
climate depends mainly on the hydraulic conductivity of the rocks and the amount of water that 
must be drained from storage in order to lower the water table. 
It is likely that equilibration to the drier climate has occurred given (1) the long time (thousands 
of years) since the climate change was completed, (2) the relatively small amount of water stored 
(small specific yield) in fractured volcanic rocks that make up much of the model domain near 
the water table, and (3) the relatively large hydraulic conductivity of the fractured volcanic rocks. 
The time required for the flow field to arrive at steady-state with respect to pumping from wells 
is much shorter than the time required for equilibration to climate change. It depends mainly on 
the time required for changes in water level to be transmitted through the SZ. Fast transmittal is 
expected in fractured volcanic rocks because of their relatively large hydraulic conductivity and 
small specific storage. The fact that the modern-day flow system has equilibrated to pumping is 
supported by the lack of consistent, large-magnitude variations in water levels observed in wells 
near Yucca Mountain (Luckey et al. 1996 [DIRS 100465], pp. 29 to 32). A transient response to 
pumping would be expected, instead, to result in a continued decrease in water levels. 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-100 November 2004 
6.5.2 Computational Model 
The FEHM software code is used in site-scale SZ modeling to obtain a numerical solution to the 
mathematical equation describing groundwater flow (Equation 6-5). FEHM is a nonisothermal, 
multiphase flow and transport code that simulates the flow of water and air and the transport of 
heat and solutes in two-dimensional and three-dimensional saturated or partially saturated 
heterogeneous porous media. The code includes comprehensive reactive geochemistry and 
transport modules and a particle-tracking capability. Fractured media can be simulated using an 
equivalent-continuum, discrete-fracture, dual-porosity, or dual-permeability approach. A subset 
of the FEHM code capabilities was used in the SZ site-scale flow model. Single-phase, 
isothermal flow was simulated in the SZ site-scale flow model. 
Particle tracking is a numerical technique that is acceptable for simulating the transport of fluid 
particles in the SZ at Yucca Mountain. Particle-tracking techniques have a long history of use in 
such applications (e.g., Pollock 1988 [DIRS 101466]; Tompson and Gelhar 1990 
[DIRS 101490]; Wen and Gomez-Hernandez 1996 [DIRS 130510]), thereby justifying this 
assumption. 
The control-volume finite element (CVFE) method is used in FEHM to obtain a numerical 
solution to the groundwater flow equation over the model domain. Finite-element methods are 
based on the assumption that a continuum may be modeled as a series of discrete elements. For 
each element, equations based on a discretized form of the groundwater flow equation are 
written that describe the interaction of that element with its neighbors. These equations describe 
the hydrologic behavior of the elements. This discretization leads to a set of equations that must 
be solved numerically to obtain the values of groundwater pressure at each node throughout the 
model domain. 
The CVFE method has been used extensively in petroleum reservoir engineering 
(Forsyth 1989 [DIRS 144110]). The CVFE method treats the potentials in a finite-element 
approach while the control-volume aspect allows local mass conservation and upstream 
weighting (Verma and Aziz 1997 [DIRS 143606]). Quadrilaterals and triangles in two 
dimensions and hexahedra and tetrahedra in three dimensions are divided into volumes 
associated with gridblocks and areas associated with interblock distances. The gridblock 
volumes are the Voronoi volumes (Forsyth 1989 [DIRS 144110]) associated with each 
gridblock. Voronoi volumes are also called perpendicular bisector volumes. The Voronoi 
volume is formed by boundaries that are orthogonal to the lines joining adjacent gridblocks and 
that intersect the midpoints of the lines (Verma and Aziz 1997 [DIRS 143606]). Any point 
within a Voronoi volume is closer to its associated gridblock than to any other node in the grid. 
The CVFE method can be shown on simple elements with constant properties to be equivalent to 
traditional finite-element methods. 
The stiffness coefficients (e.g., elements of the stiffness matrix) of the traditional finite-element 
method can be interpreted as a linear function of the area through which the fluid passes 
traveling from one node to its neighbor. A stiffness coefficient uses the area of the boundary of 
the Voronoi volume that intersects the line joining adjacent nodes. LaGriT V1.0 
STN: 10212-1.0-00 (LANL 2001 [DIRS 149148]) is designed to produce CVFE grids. 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-101 November 2004 
These terms are used to form control-volume difference equations for the conservation 
equations. This method is not traditional because equation parameters are defined by node, not 
element, but the method leads to an intuitive understanding of the numerical method. 
In FEHM, the nodal definition of equation parameters leads naturally to a separation of the 
nonlinear and purely geometric parts. This separation is explained in detail by Zyvoloski (1983 
[DIRS 101171]) and is valid over lower-order elements. The nonlinear part uses average inverse 
kinematic viscosity, 
D = 
.
 
(Eq. 6-11) 
between two nodes, which is usually taken to be the upstream nodal value. The result is a much 
more stable code for solving nonlinear problems while still retaining much of the geometric 
flexibility of finite elements. This method has been used in FEHM since 1983 (Zyvoloski 1983 
[DIRS 101171]) and has been extensively verified. A harmonic weighting of the intrinsic 
permeability is used. It is noted that even though the SZ site-scale flow model is linear, the fact 
that it uses spatially varying viscosity terms (due to spatially varying temperatures), upwinding 
the viscosity terms is the standard way of modeling the interblock fluid fluxes. The 
Newton-Raphson iteration is applied to the system of equations, which is solved with a 
multidegree of freedom and preconditioned, conjugate gradient methods using generalized 
minimum residual method or biconjugate gradient-squared acceleration techniques. 
6.5.3 SZ Site-Scale Flow Model Inputs 
The development of the base case SZ site-scale flow model involves the input of data from a 
number of sources, including water level and head distributions, definition of the hydrogeologic 
units, distribution of recharge flux and lateral fluxes into the model domain, feature and fault 
distribution, temperature profiles in wells, and boundary conditions. The data sources for these 
inputs are identified in Table 4-1. 
Incorporation of these inputs into the SZ site-scale flow model first requires the generation of a 
hydrogeologic framework conceptualization and a computational grid. The HFM 
conceptualization and known features of the site were used to design a grid for flow modeling. 
Once a computational grid is formulated, these data inputs were used to assign the hydrogeologic 
units and features, recharge fluxes, hydrogeologic properties, and boundary conditions at node 
points throughout the computation grid. Each of these elements of model development is 
discussed below. 
6.5.3.1 Hydrogeologic Framework Model Overview 
The HFM (BSC 2004 [DIRS 170008]) is a conceptual model providing a three-dimensional 
interpretation of the hydrostratigraphic unit locations and structure within the site-scale SZ flow 
and transport model domain for use in the SZ flow and transport numerical models. 
The geometry of geologic units is defined in STRATAMODEL V4.1.1, STN: 10121-4.1.1-00 
(Landmark Graphics 1998 [DIRS 153238]) framework files (DTN: GS030208312332.001 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-102 November 2004 
[DIRS 163087]) known as HFM-19, which characterize a three-dimensional geocellular model 
of the site base case HFM for the SZ (output from BSC 2004 [DIRS 170008]). In depth, the 
HFM domain extends from the interpreted potentiometric surface (DTN: GS000508312332.001 
[DIRS 149947]) to the base of the 1997 regional groundwater flow model (DAgnese et al. 1997 
[DIRS 100131]). The data in the STRATAMODEL framework files conform to the geologic 
framework model (GFM) (BSC 2004 [DIRS 170008], Section 6.3.2) in areas where the GFM is 
valid and comprises additional information for the other areas of the SZ model. The HFM-19 is 
constructed by combining a set of structural contour maps representing the tops of hydrogeologic 
units using the software product STRATAMODEL. The construction of the HFM-19 includes 
data from geologic maps and sections, borehole data, geophysical data, and existing geologic 
models. This representation enables the computational grid to be populated with an initial set of 
hydrologic properties for the calibration of the SZ site-scale flow model. The HFM-19 and its 
development are documented in Hydrogeologic Framework Model for the Saturated-Zone 
Site-Scale Flow and Transport Model (USGS 2004 [DIRS 170008]). It is noted that the base 
case HFM also includes, as its top surface, the base case water table definition. 
The HFM grid consists of a rectangular array of nodes with a spacing of 125 m. This selection 
simplifies the available data near the repository and extrapolates from very widely spaced data in 
other areas of the model domain. The three-dimensional HFM-19 was constructed by stacking 
the set of structure contour maps using geologic rules of the software STRATAMODEL. The 
software allows for the specification of sedimentary depositional units, as well as truncation and 
faulting. Stratigraphic intrusions are included by arranging the order of the stacking sequence. 
This ordering begins at a depth that is the same as the base of the HFM used to support the 
regional flow model (DTN: GS960808312144.003 [DIRS 105121]) and the granitic intrusions 
as the first geologic unit. The lower clastic confining unit was input and truncated where the 
granitic intrusions were above this grid. The remaining units were entered in order onto the 
lower clastic confining unit and intrusions, and a special surface was placed within the sequence 
to represent the thrust-faulted geometries. The valley-fill aquifer and confining units were then 
emplaced in the valleys. 
The HFM-19 was constructed to represent faults and other hydrogeologic features (such as zones 
of hydrothermal alteration) that affect SZ flow. Information on faults included fault trace maps, 
which show faults on cross sections and the locations where faults intersect the land surface. 
Faults in the model area can dip at almost any angle, but most are high-angle faults. Given 
software constraints and the numerical flow model resolution, faulting in the area was simplified, 
and the faults were treated as vertical features. Faults deemed important to flow near Yucca 
Mountain were modeled explicitly in the numerical SZ site-scale flow model. The 
hydrogeologic features that influence the flow field are identified separately 
(DTN: GS010908314221.000 [DIRS 162874]) and discussed in Section 6.5.3.4. These features 
are included in the SZ numerical model by permeability zones in FEHM. 
Important thrust faults were represented by repeating hydrogeologic units in the HFM-19. When 
geologic structural or stratigraphic surfaces are stored as arrays, they cannot have multiple 
z-values at one location. This limitation means that thrust faults and mushroom-shaped 
intrusions cannot be represented by an array. To deal with these problems, simplifying 
techniques were used. Where units were repeated by thrust faults, two different grids were 
created for the same hydrogeologic unit. A unit boundary map was then added to define an 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-103 November 2004 
outline for the perimeter of the thrust sheet. Within this boundary, hydrogeologic structural 
altitude values were treated as defining unique additional hydrogeologic unit(s). Where units 
were continuous across this boundary, altitudes of surfaces are the same on each side of the 
boundary, making the boundary invisible. Because of the large number of faults in the SZ 
site-scale model area and limitations in modeling technology, only those faults and other features 
of hydrologic importance were constructed in the HFM-19 (BSC 2004 [DIRS 170008], 
Figure 6-2). 
Most of the special features are defined as extending from the top of the carbonate aquifer to the 
top of the model (water table). Exceptions to this generalization are the Spotted Range-Mine 
Mountain zone, which extends from the top of the model to the bottom; the alluvial uncertainty 
zone, which extends from the top of the model down through the undifferentiated valley fill; and 
the Imbricate fault zone, which extends from the top of the model to the top of the 
undifferentiated valley fill (see Section 6.5.3.4, Table 6-17). 
The top of the HFM-19 is truncated by the 2000 potentiometric surface as described in 
Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (BSC 
2004 [DIRS 170008], Section 6.2). The surface contour map was constructed using 
potentiometric data from various borehole locations (BSC 2004 [DIRS 170008], Figure 6-2, 
p. 27). Data from the uppermost-completed borehole intervals were used. Borehole data for this 
HFM were estimated from the digital elevation model for data model consistency. The 
elevations were derived from USGS 3-arc-second 1-by-1 degree digital elevation model files. 
The water table forms the upper surface of the HFM-19 with grid values sampled from the 
potentiometric map to 125-m spacing coincident to the HFM. These waterlevel data have been 
updated as described in WaterLevel Data Analysis for the Saturated Zone Site-Scale Flow and 
Transport Model (BSC 2004 [DIRS 170008]). The revision consists of additional borehole 
waterlevel data and a different interpretation of the large hydraulic gradient. The 2001 
potentiometric-surface map resulting from the revision represent an alternative conceptual model 
as described in Section 6.7. 
6.5.3.2 Grid Generation 
The computational grid for the SZ site-scale flow model was developed using LaGriT 
grid-generation software. The computational grid was designed so that the horizontal grid is 
coincident with the grid cells in the 1997 flow model. The extent of the computational grid is 
shown in Figure 6-27 and Table 6-14. The depth of the computational grid is approximately the 
same as depth of DVRFS flow model. The top of the computational grid begins at the water 
table surface and extends to a depth of 2,750 m (9,020 ft) below sea level. 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-104 November 2004 
Source: DTN: GS030208312332.001 [DIRS 163087]. 
NOTE: For Illustration purposes only. This view is showing the top of the 500-m computational grid. The different 
colors in the figure show the material units as defined by hydrogeologic surfaces. The black vertical line is 
half way between the east and west boundaries and is for reference only. The grid top is the water table 
surface. 
UTM = Universal Transverse Mercator projection system of coordinates; UVA = Upper Volcanic Aquifer; 
UVCU = Upper Volcanic Confining Unit. 
Figure 6-27. Top of 500m Computational Grid 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-105 November 2004 
Table 6-14. Bounding Box 
Box Direction UTM coordinates (m) 
West to east 533,340 to 563,340 
South to north 4,046,780 to 4,091,780 
Bottom to water table 2,200 to 1,200 
Source: BSC (2004 [DIRS 170008]). 
A structural grid using orthogonal hexahedral elements is chosen for the SZ site-scale flow 
model. Previous models (Czarnecki et al. 1997 [DIRS 100377]) of Yucca Mountain SZ flow and 
transport have used both unstructured (finite element) meshes and structured orthogonal grids. 
However, the principal reason structured grids are used for this work is to allow for the use of the 
streamline particle-tracking transport capability of FEHM. Although the structured meshes are 
not as flexible as unstructured meshes in fitting complex geometry, tests have shown that they 
provide accurate solutions as long as there is adequate resolution to represent the geometry of the 
different materials in each hydrogeologic layer. Moreover, there must be enough resolution to 
account for any large gradients present in the flow or transport model. The adequacy of grid 
resolution is investigated by running a flow model using various grids of differing resolutions. If 
little difference is found among model results using grids of increasing resolution, those 
resolutions at which the model differences become minimal can be used to identify suitable grid 
resolutions. A study (Bower et al. 2000 [DIRS 149161]) of the accuracy of both the flow and 
transport solution was performed on 10 grids with horizontal resolutions ranging from 500 m to 
10,000 m to determine the appropriate horizontal grid resolution for the SZ site-scale flow 
model. Although the study was based on an earlier HFM, the results show that the 500-m grid is 
entirely adequate to meet the objectives of the SZ site-scale flow model. Consequently, a 
horizontal grid spacing of 500 m is used in this model. 
The grid resolution in the vertical dimension is important for adequately representing 
groundwater flow and transport in the SZ. Each layer in the structured grid is horizontal, but the 
layers of the physical hydrogeologic units are gently sloping with approximately 7 percent dip to 
the east. Therefore, a finer and nonuniform grid resolution is used in the vertical dimension, and 
this is sufficient to capture the geometry of the hydrogeologic units. The vertical grid spacing is 
selected to provide the resolution for accurately representing flow and transport along critical 
flow and transport pathways in the SZ. A finer resolution is used at shallower portions of the 
model, and a progressively coarser resolution is used for deeper portions of the aquifer. The 
vertical grid spacing ranges from 10 m (33 ft) near the water table to 550 m (1,805 ft) at the 
bottom of the model domain. The vertical dimension of the model domain is divided into 
11 zones, and constant vertical grid spacing is adopted in each of these zones. The structure of 
the vertical layering used in the site-scale SZ flow and transport model grid is summarized in 
Table 6-15 and shown in the full three-dimensional view Figure 6-28. In total, 38 layers are 
included in the vertical dimension that extends from +1,200 m (4,100 ft) to -2,750 m (-9,020 ft) 
elevation. Figure 6-29 shows a close-up view of the horizontal and vertical resolution in the 
grid. The material properties were assigned to the intersections of the grid lines. At the 
locations where grid is coarse, some of the HFM-19 layers were not represented. However, in 
the areas of most interest, the grid is very fine and the resolution of the HFM-19 is on the same 
level as the resolution of the grid. 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-106 November 2004 
Table 6-15. Vertical Grid Spacing Used in the SZ Site-Scale Flow Model 
Gridblock Elevation Zone 
Boundaries (m) 
Upper Lower 
Grid 
Spacing 
(m) 
Zone Width 
(m) 
Grid Lines 
per Zone 
1200 1000 50 200 4 
1000 840 40 160 4 
840 760 20 80 4 
760 700 10 60 6 
700 640 20 60 3 
640 600 40 40 1 
600 300 50 300 6 
300 0 100 300 3 
0 600 200 600 3 
600 2200 400 1600 4 
2200 2750 550 550 1 
Total: 39 
Output DTN: LA0304TM831231.002. 
NOTE: Of the 39 grid lines, one defined the lower boundary of the model 
and, thus, was not considered in the model. Therefore, there were 
only 38 grid lines in the model. 
Anisotropy in the horizontal permeability field (north-south and east-west components) is 
assumed to be sufficient to represent fracture sets at the sub-grid scale. The use of just the 
principal values of permeability without cross terms is justified because this form of anisotropy 
is to represent the predominately north-south trending faults east of Yucca Mountain and west of 
Fortymile Wash (BSC 2004 [DIRS 170015], Figure 6-6). Because of the fault direction 
(see Section 6.6.1.3), they only enhance the north-south flow in that region (for illustration 
purposes only). 
A three-dimensional representation of the computational grid is provided in Figure 6-28. Not all 
unit layers extend throughout the entire horizontal extent of the model domain. Because the 
model domain is both truncated at the water table and the water table exhibits some variation in 
altitude over the model domain (700 m to 1,200 m), those layers in the higher water table areas 
(i.e., to the north of the model domain) are truncated as the water table decreases in altitude 
toward the south. 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-107 November 2004 
N 
Source: DTN: GS030208312332.001 (DIRS 163087). 
NOTE: The grid is truncated at the water table surface, which is at 1,200 m in the north and 700 m in the south. 
The grid extends 533,340 to 563,340 m in the east and west, and 4,046,780 to 4,091,780 m north and 
south (Coordinates UTM North American Datum 27). 
Figure 6-28. View of the 500m Computational Grid (3x Vertical Exaggeration) Showing Node Points 
Colored by Hydrogeologic Unit Values from the HFM-19 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-108 November 2004 
Source: DTN: GS030208312332.001 (DIRS 163087). 
NOTE: For illustration purposes only. Grid spacing at the bottom of the grid is at 400 m, then 200, 100, 50, 40, 20, 
with 10 m near an elevation of 700 m. Spacing then increases with elevation from 10 m to 20 and 40 m, 
with 50-m spacing near the higher elevations in the north. The inset at the bottom of the image shows the 
location of the cut out in relation to the full grid. The grid points are colored with the values of the 
Hydrogeologic Units 2 through 20. Elevations are denoted in the figure from -1,400 to 700 m above mean 
sea level. 
UTM = Universal Transverse Mercator 
Figure 6-29. Close-Up View of Computational Grid (3x Vertical Exaggeration) Showing Cut Away at 
UTM Easting = 549000 and UTM Northing = 4078000 Through the Yucca Mountain 
Repository 
-600 
0 
600 
700 
-1400 
N

SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-110 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: See notes following Figure 6-36. 
HFM = Hydrogeologic Framework Model; UTM = Universal Transverse Mercator 
Figure 6-30. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Units 2, 3, 4 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-111 November 2004 
Output DTN: LA0304TM831231.002 
NOTE: See notes following Figure 6-36. 
HFM = Hydrogeologic Framework Model ; UTM = Universal Transverse Mercator. 
Figure 6-31. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Units 5, 6, 7 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-112 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: See notes following Figure 6-36 
HFM = Hydrogeologic Framework Model ; UTM = Universal Transverse Mercator. 
Figure 6-32. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Units 8. 9, 10 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-113 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: See notes following Figure 6-36. 
HFM = Hydrogeologic Framework Model; UTM = Universal Transverse Mercator. 
Figure 6-33. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Units 11, 12, 13 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-114 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: See notes following Figure 6-36. 
HFM = Hydrogeologic Framework Model; UTM = Universal Transverse Mercator 
Figure 6-34. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Units 14, 15, 16 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-115 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: See notes following Figure 6-36. 
HFM = Hydrogeologic Framework Model; UTM = Universal Transverse Mercator. 
Figure 6-35. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Units 17, 18, 19 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-116 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: Left panels of HFM-19 Layer Thicknesses: Color in the grid indicates vertical thickness between each of 
two unit surfaces. Each image is a plan view of the input HFM-19 and is formed by the surfaces extracted 
from the HFM-19. The bottom surface of each hydrogeologic unit is subtracted from the top surface 
resulting in the unit thickness at each point. Points of zero thickness have been removed, and the points 
are shown in relation to the topographic surface. These points are at a resolution of 125 m, the same as 
the HFM (BSC 2004 [DIRS 170008], Section 6.1). 
Right panels of Grid Nodes by Hydrogeologic Unit: Color in the grid indicates elevation at the top of the 
unit. Each image is a view looking down at the 500-m computational grid. Images are formed by selecting 
node points for each of the unit numbers 2 through 20. There are no points where the units are truncated. 
Output DTN: LA0304TM831231.002 
Correspondence between hydrostratigraphic unit numbers and unit names is listed in Figure 6-14. 
HFM = Hydrogeologic Framework Model; UTM = Universal Transverse Mercator. 
Figure 6-36. Composition of HFM-19 and SZ Site-Scale Flow Model Units Thickness for Unit 20 
The LaGriT code writes FEHM input files; these files include the mesh geometry, lists of nodes 
on external boundaries, and node lists sorted by hydrogeologic unit. The number of nodes 
assigned to each hydrogeologic unit is presented in Table 6-16. 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-117 November 2004 
Table 6-16. Number of Gridblocks per Hydrogeologic Unit 
Surface 
Number Hydrogeologic Units 
Number of 
Gridblocks 
20 Alluvium (Valley-Fill Aquifer) 6,188 
19 Valley-Fill Confining Unit 13 
18 Limestones 227 
17 Lava Flows 891 
16 Upper Volcanic Aquifer 13,831 
15 Upper Volcanic Confining Unit 7,845 
14 Crater Flat  Prow Pass 5,666 
13 Crater Flat  Bullfrog 6,472 
12 Crater Flat  Tram 11,676 
11 Lower Volcanic Confining Unit 9,142 
10 Older Volcanic Aquifer 210 
9 Older Volcanic Confining Unit 11,012 
8 Undifferentiated Valley Fill 21,578 
7 Upper Carbonate Aquifer 23 
6 Lower Carbonate Aquifer Thrust 1,192 
5 Upper Clastic Confining Unit 5,923 
4 Lower Carbonate Aquifer 27,097 
3 Lower Clastic Confining Unit 13,259 
2 Granitic confining unit 608 
1 Base 0 
Total Number of Gridblocks 142,853 
Output DTN: LA0304TM831231.002. 
6.5.3.4 Features 
To represent discrete features and regions having distinct hydrological properties within the 
model domain, a set of 17 hydrogeologic features complementary to the HFM were identified 
and incorporated into the flow model. The hydrogeologic features included in the SZ site-scale 
flow model primarily represent faults, fault zones, and areas of mineralogical alteration. The 
features described here are essentially vertical: some being linear in the horizontal extent, and 
some being of areal extent. These features are distinct from the subhorizontal geological 
formations, which form zones with distinct geometry and material properties and are described in 
Section 6.5.3.3. Each of the features described in this report includes multiple geologic 
formations and represents zones of altered permeability within the individual 
formations: enhanced permeability, reduced permeability, or anisotropic permeability. Each 
feature has a significant impact on the SZ site-scale flow model. The geometric definition, 
description, nature of permeability alteration, and impact on the model for each of these features 
are described in Table 6-17. In the table, the numbers in the parentheses refer to zone numbers 
in the input file for FEHM. The features are shown in Figure 6-37, which is based on the Yucca 
Mountain area geologic map (DTN: GS010908314221.001 [DIRS 162874]) and shows feature 
representation in the SZ site-scale flow model. Also shown in the figure are the zone numbers 
used in the input files for FEHM. The permeability values associated with the features described 
in Table 6-17 are presented and discussed in Section 6.6.1.4. Because of their importance to 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-118 November 2004 
TSPA, two proposed zones in the alluvium deserve special consideration. These zones are 
(1) the alluvial uncertainty zone and (2) the lower Fortymile Wash zone. The alluvial 
uncertainty zone was added to incorporate the new geology obtained with the recently drilled 
NC-EWDP-2D and Washburn wells (DTN: MO9909NYEEWDP0.000 [DIRS 119613]). This 
data source is not direct input to the SZ site-scale flow model. It is cited only to support the 
assertion that the base case HFM does not accurately represent the volcanic alluvium contact in 
the vicinity of the above-mentioned wells. The location of this zone is given in Table 6-17. The 
drilling records of these wells show that alluvium extends further north and east than the 
geologic model (created without benefit of the two wells) indicates. Because of the importance 
to TSPA, the alluvial uncertainty zone was added to the model. The lower Fortymile Wash zone 
was added because of the distinct character of the Fortymile Wash in the southern part of the 
model. Field observations indicate possible channelization with attendant textural contrasts with 
surrounding alluvial material (Oatfield and Czarnecki 1989 [DIRS 149438]). 
The Claim Canyon, Calico Hills, Shoshone Mountain fault zones (known collectively as the 
northern low permeability zone), and the east-west barrier deserve additional comment because 
they form the LHG zone (Luckey et al. 1996 [DIRS 100465]) north of Yucca Mountain. The 
east-west barrier was required to have a low permeability (10-18 m2) during the calibration in 
order to separate the high heads in the north from the lower heads near Yucca Mountain. This 
feature has no other geologic significance. Though there are several theories proposed to explain 
the large hydraulic gradient, the expert elicitation panel (CRWMS M&O 1998 [DIRS 100353], 
pp. 3-5 to 3-6) favored the idea of semi-perched water in that area. If several of the wells were 
semi-perched to the north of Yucca Mountain, then the hydraulic head gradient in the SZ would 
be smaller. This would likely result in different calibrated values for the northern low 
permeability zone and the east-west barrier than those obtained with the present model. 
6.5.3.5 Boundary and Initial Conditions 
The lateral boundary conditions are described in Section 6.3.2.6. It should be noted that, 
historically, groundwater has been extracted from wells in the Amargosa Valley south of the 
site-scale model domain. Drawdown from the wells is represented in the 2000 potentiometric 
surface map that was used to establish southern boundary head conditions. Consequently, the 
effect of pumping on flow within the model domain is accounted for by the head values specified 
along the southern boundary. A small amount of pumping also has occurred from the southern 
portion of the site-scale model. This pumping was included in the DVRFS model, but not the 
site-scale model. Ignoring this pumping is assumed to have very little effect on the calculated 
flow paths and flow times to compliance boundaries. 
The initial conditions (initial pressure or head distribution) are not relevant since the SZ 
site-scale flow model and all the alternative models are formulated for steady-state flow. 

MDL-NBS-HS-000011 REV 02 6-119 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-17. Hydrological Features in the SZ Site-Scale Flow Model 
Feature Name and Description 
Geometric Definition 
(UTM) 
Hydrogeological 
Characteristics Impact on Model 
1. Northern Zone (Entire Claim Canyon, 
Calico Hills, and Shoshone Mountain.; #81) 
This zone is wedge-shaped, spanning almost the entire 
northern boundary (except the western corner of the northern 
boundary) and approximately the upper fourth of the eastern 
boundary. Vertically, it extends from the top to the bottom of 
the model, and its areal extent is shown by the four points. 
x = 546436, y = 4082110, 
x = 563657, y = 4082110, 
x = 563549, y = 4092080, 
x = 535832, y = 4092020, and 
z = top to bottom of model. 
It represents the general region 
of lowered permeability caused 
by hydrothermal alteration 
associated with the Claim 
Canyon caldera. 
Impact of the model on this 
zone is mainly to control the 
flow of water into the model 
from the north boundary. 
2. Northern Crater Flat Zone (#82) 
This wedge-shaped zone is at the northern third of the 
western boundary of the model. Vertically, it extends from 
the top to the bottom of the model, and its areal extent is 
shown by the four points. 
x = 533077, y = 4074580, 
x = 544206, y = 4074530, 
x = 544103, y = 4083490, 
x = 532974, y = 4092230, and 
z = top to bottom of model. 
It is a permeability reduction 
zone, representing a 
hydrothermally altered area 
associated with the Claim 
Canyon caldera. 
Impact of the model on this 
zone is to control influx from 
the northwest corner of the 
model. 
3. Fortymile Wash Zones (#57 and #58) 
These two north-south linear features are located 
approximately halfway between Yucca Mountain and the 
eastern model boundary. Vertically, they extend from the top 
to the bottom of the model, and their areal extent is shown by 
the four points. 
x = 554330, y = 4066770, 
x = 554350, y = 4066770, 
x = 554350, y = 4081790, 
x = 554330, y = 4081790, and 
z = top to bottom of model. 
It is an enhanced permeability 
zone representing the faulted 
area associated with the wash. 
Impact on the model is to 
channel the flow of the 
east-central portion of the 
model in the Jackass Flats 
area in a southern direction, 
lower the hydraulic gradient 
in the area, and act as a 
regional drain. 
4. Spotted Range-Mine Mountain Zone (#59) 
This triangular feature is in the southeast corner of the 
model. Vertically, it extends from the top of the model down 
to the bottom. Its areal extent is shown by the four points. 
x = 555000, y = 4046770, 
x = 563350, y = 4046770, 
x = 563350, y = 4059000, 
x = 563310, y = 4059000, and 
z = top to bottom of model. 
It is a zone of enhanced 
permeability associated with 
the Spotted Range thrust 
region 
Impact on the model is to 
control the water flow into the 
model from the southern end 
of the east boundary and 
water flow out of the model of 
the eastern end of the 
southern boundary. 
MDL-NBS-HS-000011 REV 02 6-120 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-17. Hydrological Features in the SZ Site-Scale Flow Model (Continued) 
Feature Name and Description 
Geometric Definition 
(UTM) 
Hydrogeological 
Characteristics Impact on Model 
5. Claim Canyon Caldera (East and West, #61 and #62) 
These zones span much of the northern boundary of the 
model, extending south as triangular shapes and terminating 
north of the Yucca Wash. Vertically, they extend from the 
top to the bottom of the model, and their areal extent is 
shown by the eight points. These zones are part of the 
northern low perm zone used in calibration. 
x = 536800, y = 4091760, 
x = 540000, y = 4086700, 
x = 547600, y = 4084700, 
x = 547600, y = 4091760; and 
x = 547677, y = 4091760, 
x = 547631, y = 4084710, 
x = 560000, y = 4087660, 
x = 560000, y = 4091760, and 
z = top to bottom of model. 
These are zones of reduced 
permeability due to the 
hydrothermal alteration 
associated with the caldera; but 
the permeability reduction is 
somewhat less than the rest of 
the northern zone, probably due 
to faulting associated with the 
vertical movement due to caldera 
collapse and the greater 
thickness of welded zones within 
the caldera. 
Impact on the model is 
mainly to control the water 
flow into the model from the 
northern boundary. 
6. Shoshone Mountain Zone (North and South, #63 and 
#64) 
These two zones are in the northeastern corner of the model. 
They extend from the top of the carbonate aquifer up to the 
top of the model. Vertically, they extend from the top to the 
bottom of the model, and their areal extent is shown by the 
eight points. These zones are part of the northern low perm 
zone used in calibration. 
x = 560634, y = 4091530, 
x = 559362, y = 4089570, 
x = 563090, y = 4089620, 
x = 563044, y = 4091480; and 
x = 557045, y = 4089620, 
x = 560953, y = 4087480, 
x = 563137, y = 4087750, 
x = 563090, y = 4089620, and 
z = top to bottom of model. 
These are zones of permeability 
reduction due to hydrothermal 
alteration associated with the 
Claim Canyon caldera. 
Impact on the model is 
mainly to control the water 
flow into the model from the 
northern portion of the 
eastern boundary. 
7. Calico Hills Zone (North and South #65 and #66) 
These two zones are near the eastern end of the model, 
south of the Shoshone Mountain zones, at approximately the 
same northing as the Yucca Wash. Vertically, they extend 
from the top to the bottom of the model, and their areal 
extent is shown by the eight points. These zones are part of 
the northern low perm zone used in calibration. 
x = 556864, y = 4081020, 
x = 562957, y = 4081020, 
x = 561499, y = 4084070, 
x = 558589, y = 4083430; and 
x = 556818, y = 4081020, 
x = 558821, y = 4078070, 
x = 561273, y = 4077160, 
x = 563142, y = 4080980, and 
z = top to bottom of model. 
These are zones of permeability 
reduction due to hydrothermal 
alteration associated with the 
Calico Hills 
Impact on the model is 
mainly to control the water 
flow into the model from the 
northern portion of the 
eastern boundary. 
MDL-NBS-HS-000011 REV 02 6-121 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-17. Hydrological Features in the SZ Site-Scale Flow Model (Continued) 
Feature Name and Description 
Geometric Definition 
(UTM) 
Hydrogeological 
Characteristics Impact on Model 
8. Crater Flat Fault (North-1, North-2, South-3, and 
South-4, #69, #70, #71, and #72) 
This is a linear feature running north-south in the western 
half of the model, starting to the south of the Claim Canyon 
and terminating near U.S. Highway 95, almost halfway 
between the western boundary and the Solitario Canyon. 
Vertically, it extends from the top to the bottom of the model, 
and its areal extent is shown by the sixteen points. 
x = 538330, y = 4083800, 
x = 538350, y = 4083800, 
x = 538350, y = 4089430, 
x = 538330, y = 4089430; and 
x = 538330, y = 4074750, 
x = 538350, y = 4074750, 
x = 538350, y = 4083800, 
x = 538330, y = 4083800; and 
x = 538330, y = 4066500, 
x = 538350, y = 4066500, 
x = 538350, y = 4074750, 
x = 538330, y = 4074750; and 
x = 538330, y = 4061400, 
x = 538350, y = 4061400, 
x = 538350, y = 4066500, 
x = 538330, y = 4066500; and 
z = top to bottom of model. 
These are zones of permeability 
reduction normal to the fault 
orientation and permeability 
enhancement parallel to the fault 
orientation. 
Impact on the model of these 
zones is to generate a 
somewhat high head gradient 
in the western half of the 
model and control the influx 
coming from the western 
boundary, and to restrict the 
flow towards the eastern half 
of the model. 
9. Solitario Canyon Fault (#74, # 83 and #84) 
These are generally north-south trending linear features just 
to the west of Yucca Mountain. Vertically, they extend from 
the bottom of the model to the top of the model. Their areal 
extent is shown by the twelve points. 
x = 546451, y = 4077540, 
x = 545632, y = 4073550, 
x = 546384, y = 4073550, 
x = 547018, y = 4077540; and 
x = 546451, y =4077540, 
x = 545632, y = 4077520, 
x = 546384, y = 4081580, 
x = 547018, y = 4081580; and 
x = 545638, y = 4071110, 
x = 546379, y = 4071080, 
x = 546647, y = 4073550, 
x = 546008, y = 4073520; and 
z = top to bottom of model. 
These are zones of permeability 
enhancement in the vertical and 
fault-parallel direction and 
permeability reduction normal to 
the fault. 
Impact on the model of these 
features is to generate a 
higher head gradient to the 
west of Yucca Mountain and 
to impede flow from Crater 
Flat to Yucca Mountain. 
10. Solitario Canyon Fault, East Branch (#75, #76) 
These are generally north-northeast trending linear features 
just to the west of Yucca Mountain. Vertically, they extend 
from the bottom of the model to the top of the model. Their 
areal extent is given by the eight points. 
x = 545632, y = 4071110, 
x = 547450, y = 4064680, 
x = 547996, y = 4064680, 
x = 546384, y = 4071090; and 
x = 547450, y = 4064680, 
x = 544520, y = 4058330, 
x = 545040, y = 4058150, 
x = 548022, y = 4064680; and 
z = top to bottom of model. 
These are zones of permeability 
enhancement in the vertical and 
fault-parallel direction and 
permeability reduction normal to 
the fault. 
Impact on the model of these 
features is to generate a 
higher head gradient to the 
west of Yucca Mountain and 
to impede flow from Crater 
Flat to Yucca Mountain. 
MDL-NBS-HS-000011 REV 02 6-122 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-17. Hydrological Features in the SZ Site-Scale Flow Model (Continued) 
Feature Name and Description 
Geometric Definition 
(UTM) 
Hydrogeological 
Characteristics Impact on Model 
11. Solitario Canyon Fault, West Branch (#77, #78) 
These are generally north-northeast trending linear features 
just to the west of Yucca Mountain. Vertically, they extend 
from the bottom of the model to the top of the model. Their 
areal extent is given by the eight points. 
x = 545632, y = 4061090, 
x = 540452, y = 4062590, 
x = 541018, y = 4062610, 
x = 546384, y = 4071060; and 
x = 540426, y = 4062590, 
x = 540132, y = 4059720, 
x = 540699, y = 4059470, 
x = 541018, y = 4062590; and 
z = top to bottom of model. 
These are zones of permeability 
enhancement in the vertical and 
fault-parallel direction and 
permeability reduction normal to 
the fault. 
Impact on the model of these 
features is to generate a 
higher head gradient to the 
west of Yucca Mountain and 
to impede flow from Crater 
Flat to Yucca Mountain. 
12. U.S. Highway 95 Fault (West, #79) 
This is a linear feature in the lower half of the western portion 
of the model. It is east-southeast trending. Vertically, it 
extends from the bottom of the model to the top of the model. 
Its areal extent is given by the four points. 
x = 536625, y = 4061240, 
x = 544355, y = 4058380, 
x = 544716, y = 4058330, 
x = 536486, y = 4061840, and 
z = top to bottom of model. 
This is a zone of permeability 
enhancement in the vertical and 
fault-parallel direction and 
permeability reduction normal to 
the fault. 
Impact on this model is to 
restrict flow in the north-south 
direction and support high 
head gradients in that portion 
of the model. 
13. Bare Mountain Fault (#80 and #90) 
This is a northwest- to southeast-trending linear feature in 
the southwestern corner of the model. Vertically, it extends 
from the bottom of the model to the top of the model. Its 
areal extent is given by the eight points. 
x = 533628, y = 4067570, 
x = 536126, y = 4061020, 
x = 536672, y = 4061250, 
x = 533628, y = 4068980, and 
x = 540330, y = 4046780, 
x = 540850, y = 4046780, 
x = 533850, y = 4064290, 
x = 533330, y = 4064290; and 
z = top to bottom of model. 
This is a zone of permeability 
enhancement representing the 
Bare Mountain fault. 
Impact on the model is to 
drain the flow from Crater 
Flat to the Amargosa Desert. 
14. Alluvial Uncertainty Zone (Expected Case, #88) 
This is a roughly rectangular region to the south of Yucca 
Mountain in the southern half of the model. Vertically, it 
extends from the top of the model down through the 
undifferentiated units. Its areal extent is given by the four 
points. 
x = 547622, y = 4057310, 
x = 555503, y = 4055420, 
x = 556740, y = 4062060, 
x = 550691, y = 4062060, and 
z = top of model to +400. 
This zone represents uncertainty 
in the border between the 
alluvium and tuff. 
Although it does not strongly 
influence the SZ site-scale 
flow model, it is expected to 
be important to TSPA 
calculations due to its effect 
on solute transport. 
15. Imbricate Fault Zone (#91) 
This is a highly faulted area bounded in the west by the 
Ghost Dance fault, south by the Dune Wash, east by the 
Paintbrush Canyon fault, and to the north by the Drill Hole 
Wash. Vertically, it extends from the top of the model down 
through the middle volcanics to the top of the undifferentiated 
units. Its areal extent is given by the four points. 
x = 548830, y = 4073270, 
x = 552350, y = 4071770, 
x = 552350, y = 4077290, 
x = 548830, y = 4079790, and 
z = top of model to +400. 
This is a region of permeability 
enhancement. 
It allows the model to 
represent higher 
permeabilities due to faulting 
while retaining regional scale 
permeability values of the 
middle volcanic layers in the 
expected range. 
MDL-NBS-HS-000011 REV 02 6-123 November 2004 
Saturated Zone Site-Scale Flow Model 
Table 6-17. Hydrological Features in the SZ Site-Scale Flow Model (Continued) 
Feature Name and Description 
Geometric Definition 
(UTM) 
Hydrogeological 
Characteristics Impact on Model 
16. East-West Barrier (#56) 
This linear feature runs east-west just to the north of Yucca 
Mountain, starting at the western edge of Yucca Mountain 
and extending eastwards but short of the Calico Hills. 
Vertically, it extends from the bottom of the model to the top 
of the model. Its areal extent is given by the four points. 
x = 546000, y = 4081440, 
x = 559000, y = 4081440, 
x = 559000, y = 4082000, 
x = 546000, y = 4082000, and 
z = top to bottom of model. 
This is a zone of permeability 
reduction. 
The impact of this barrier on 
the model is mainly to create 
the steep hydraulic gradient 
to the north of Yucca 
Mountain between the wells 
G2, WT6 to the north and the 
wells WT18, H1 to the south. 
17. Lower Fortymile Wash Zone (#45) 
This quadrilateral feature (plan view) encompasses the lower 
Fortymile Wash part of the model. The depth of the zone 
includes the alluvium unit to the top of the model. Its areal 
extent is given by the four points. 
x = 546965, y = 4057460, 
x = 550691, y = 4056450, 
x = 547893, y = 4046760, 
x = 540833, y = 4046760, 
z = 400m to top. 
This is a zone of permeability 
enhancement. 
The impact on the model of 
this barrier is mainly to create 
the low hydraulic gradient 
observed in the Fortymile 
wash area where it intersects 
the southern boundary. 
Sousre : DTN: GS010908314221.001 (DIRS 162874); Output DTN: LA0304TM831231.002. 
NOTE: The geologic map in DTN GS010908314221.001 [DIRS 162874] is an essential input used to construct a site-scale three-dimensional hydrologic 
framework model (HFM), (BSC 2004 [DIRS 170008]). The geographic coordinates and the name of the different geologic features shown in this table are 
the results of interpretation of the geologic map, including geologic cross-sections, and lithostratigraphic and structural data from boreholes as it is 
described in detail in BSC (2004 [DIRS 170008]). The conversion of the geographic coordinates was done using standard Geographic Information 
System (GIS) functions. An example shows both the latitude/longitude and UTM coordinates of the site-scale model and some of the features shown in 
Figure 6-37 (BSC 2004 [DIRS 170008], Figure 6-3). 
TSPA=total system performance assessment; UTM = Universal Transverse Mercator 

MDL-NBS-HS-000011 REV 02 6-124 November 2004 
Saturated Zone Site-Scale Flow Model 
Source: DTN: GS010908314221.001 (left panel) [DIRS 162874]. Output DTN: LA0304TM831231.002 (right panel). 
NOTE: Fault traces are on the left panel, and the SZ model representation is on the right panel. Numbers designate the following regions: 45 - lower Fortymile 
Wash zone; 56 -east-west Barrier zone; 57 and 58 - Fortymile Wash zones; 59 - Spotted Range-Mine Mountain zone; 61 and 62 - Claim Canyon caldera 
zones; 63 and 64 - Shoshone Mountain zones; 65 and 66 - Calico Hills zones; 69, 70, 71, and 72 - Crater Flat fault zones; 74, 83, and 84 - Solitario 
Canyon fault zones; 75 and 76 - Solitario Canyon fault zones (east branch); 77 and 78 - Solitario Canyon fault zones (west branch); 79 - U.S. Highway 95 
fault zone; 80 and 90 - Bare Mountain fault zones; 81 - northern zone; 82 - northern Crater Flat zone; 88 - alluvial uncertainty zone (expected case); 91 - 
Imbricate fault zone. 
The geologic map in DTN GS010908314221.001 [DIRS 162874] is an essential input used to construct the site-scale three-dimensional hydrologic 
framework model (HFM-19), (BSC 2004 [DIRS 170008]). The geographic coordinates and the name of the different geologic features shown in this figure 
are the results of interpretation of the geologic map, including geologic cross-sections, and lithostratigraphic and structural data from boreholes as it is 
described in detail in BSC (2004 [DIRS 170008]). The conversion of the geographic coordinates was done using standard Geographic System Information 
(GIS) functions. See Figure 6-3 in BSC (2004 [DIRS 170008]) an example showing both, the latitude/longitude and UTM coordinates of the site-scale 
model and some of the features shown in Figure 6-37. 
UTM = Universal Transverse Mercator 
Figure 6-37. Geologic Features in the Area of the SZ Site-Scale Flow Model 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-125 November 2004 
6.5.3.6 Recharge 
Recharge was applied to the top surface of the computational grid as a flux boundary condition. 
The recharge map in Recharge and Lateral Groundwater Flow Boundary Conditions for the 
Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015], Section 6.2) 
was mapped (with changes to be described later) to the top surface of the numerical grid 
described in this report. An important characteristic of the recharge data is that they were 
developed with the assumption that they are applied at the lands surface. The recharge data 
required as impacts to the SZ site-scale flow model are the penetration rate at the water table 
infiltration. The exception is the recharge in the area of the UZ model domain, where the actual 
output of the UZ model was used. Thus, except for the area beneath the UZ model domain, 
redistribution of infiltration in the UZ is likely to produce recharge at the water table that is 
different from that described in Recharge and Lateral Groundwater Flow Boundary Conditions 
for the Saturated Zone Site-Scale Flow and Transport Model (BSC 2004 [DIRS 170015]). 
Because most of the recharge occurs at higher elevations in rocks that are less permeable than in 
other regions, there are nodes at the top of the model (i.e., at the water table surface) where the 
permeability is too small to accept the recharge developed for the land surface at that location. 
This has necessitated the increase in the permeability of the top layer in the SZ model in some 
areas. This change allows the flow to redistribute locally and avoid artificially high heads. This 
method conserved recharge mass flux and was deemed better than any procedure that would 
modify the spatial distribution of the recharge. Sensitivity to this procedure on calibration and 
flow direction is small because this procedure was applied to the low permeability rocks that 
exist to the north of Yucca Mountain. The effect on the flow field to the south and east of Yucca 
Mountain, provided the heads and gradients are well matched, is therefore minimal. 
To assign recharge values to the top surface of the computational grid, an infiltration map 
(DTN: SN9908T0581999.001 [DIRS 132867]) was interpolated onto the computational mesh to 
provide the top surface flux boundary condition. The interpolation procedure was designed to 
ensure that the local small-scale features of the infiltration map are represented in the boundary 
conditions and that the total flux is preserved. This procedure is accomplished by first providing 
the infiltration map (DTN: SN9908T0581999.001 [DIRS 132867]) as an ASCII file with two 
coordinates, x and y, for each data point, the area associated with that point, and the infiltration 
rate for each point. The computational mesh has a regular point distribution with points spaced 
at 500-m horizontal intervals. However, the mesh numbering was irregular. A geometric sorting 
program was used to identify each point in the infiltration data with the corresponding gridlock 
in the computational mesh. This step is equivalent to determining the gridblock number for the 
500-m mesh and determining to which node each point of the infiltration map belongs. 
Figure 6-38 shows a comparison of the data in the above-mentioned DTN and that recharge used 
in the FEHM input files for the SZ site-scale flow model. They are identical, thus proving that 
the mapping used preserves the recharge distribution. 
6.5.3.7 Nodal Hydrogeologic Properties 
Hydrogeologic properties must be specified for each node in the computational grid. Using the 
hydrogeologic unit sets created in the grid-building process, flow parameters such as 
permeability, viscosity, and porosity are assigned to each node. 
The parameter values for viscosity depend on the temperature at each node, and a uniform 
temperature gradient is assumed. This assumption of a uniform temperature gradient with depth 
SZ Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-126 November 2004 
is equivalent to assuming uniform geothermal heat flux through a medium of homogeneous 
thermal conductivity. In addition, the temperature at the ground surface is assumed to be equal 
to a uniform value. The data on temperature in boreholes presented by Sass et al. (1988 
[DIRS 100644]; DTN: MO0102DQRBTEMP.001 [DIRS 154733], Figures 4, 5, 6, 7, 8, and 10) 
indicate that there is significant variability in the temperature gradient at different locations and 
within individual wells, presumably from advective redistribution of heat from infiltration and 
vertical groundwater flow. The data were used to estimate an approximate average temperature 
gradient and representative surface temperature for the site. As noted by Sass et al. (1988 
[DIRS 100644], p. 2), there is considerable variability (about 15C/km to nearly 60C/km) in the 
temperature gradients among the wells. However, the approximately average value of the 
temperature gradient in the wells is 25C/km, and the average surface temperature is about 19C. 
However, these data also indicate that the temperature gradients generally become more linear 
with increasing depth below the water table. It is important to note that the goal of assigning 
temperature variations with depth in the SZ site-scale flow model is to account for resulting 
variations in fluid viscosity at different depths in the SZ. The viscosity of water changes by a 
factor of only about 3.3 over the temperature range of 20C to 100C (Streeter and Wylie 1979, 
[DIRS 145287], p. 536) that is expected within the range of depths in the SZ site-scale model 
domain. Thus, the linear approximation of the temperature gradient is adequate to capture the 
general effects of variations in groundwater viscosity with depth in the SZ site-scale flow model. 
The density also varies with temperature, but the effect is much smaller than that of viscosity. 
Over the temperature range of 20C to 100C, water density varies only a few percent, and 
therefore density was treated as a constant. Using a variable viscosity allows the calibration of 
intrinsic permeability to be made instead of hydraulic conductivity. The former is a rock 
property, whereas the latter is both a rock and fluid property. This approach, in turn, allows for 
more accurate flux calculations on the boundaries of the model. 
The approach taken to the incorporation of groundwater temperature in the SZ site-scale model 
was to evaluate the average temperature gradient using temperature measurements in boreholes 
and to use that temperature gradient to specify temperature at grid nodes in the SZ site-scale flow 
model. As implemented in the SZ site-scale flow model, temperatures remain fixed at the 
specified value, and the heat-transport equations are not solved in the simulation. Thus, the 
specified values of temperatures were used to calculate the local groundwater viscosity, but 
temperature variations do not result in any variable-density flow processes as the density in all 
calculations was treated as a constant. 
The temperature at the water table at the different locations was calculated as the sum of the 
representative temperature at the surface (19C) and the product of the average temperature 
gradient (25C/km) and the depth to the water table. The depth to water table in the different 
boreholes was calculated as the difference in the surface elevation of the borehole and the 
calculated average ground water table altitude. The data on the borehole locations, surface 
elevations, and the average groundwater table altitudes were taken from 
DTN: GS010908312332.002 [DIRS 163555]. The map in Figure 6-39 shows spatial 
distribution of the temperatures at the water table generated from the point temperatures at the 
water table calculated at the borehole locations. The lower temperatures in this figure 
correspond to areas of relatively small-unsaturated thickness, and the higher temperatures 
correspond to a thick UZ. 
MDL-NBS-HS-000011 REV 02 6-127 November 2004 
Saturated Zone Site-Scale Flow Model 
Source DTN: SN9908T0581999.001 [DIRS 132867] (left panel). Output DTN: LA0304TM831231.002 (right panel). 
NOTE: The contoured recharge rate refers to an area of 500  500 m2, and that a recharge rate of 0.2 kg/s corresponds to a recharge flux of approximately 
25 mm/yr. 
UTM = Universal Transverse Mercator 
Figure 6-38. Comparison of Recharge Data (Left Panel) with Those Used as Input in the SZ Site-Scale Flow Model Data (Right Panel)
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-128 November 2004 
Source: DTN: MO0102DQRBTEMP.001 [DIRS 154733]. 
NOTE: UTM = Universal Transverse Mercator 
Figure 6-39. Map of Modeled Temperature at the Water Table for the SZ Site-Scale Flow Model Domain 
6.6 SZ SITE-SCALE FLOW MODEL RESULTS 
6.6.1 Model Calibration 
Calibration is the process by which values of important model parameters are estimated and 
optimized to produce the best fit between the model output and the observed data. Calibration 
generally is accomplished by adjusting model input parameters (e.g., permeability) to minimize 
the difference between observed and simulated conditions (in this case, comparing predicted and 
observed head values and lateral boundary fluxes). Model calibration may be performed through 
manual methods or automated optimization procedures. Automated optimization procedures 
generally employ a carefully prescribed mathematical process that selects the optimal set of 
parameters based on minimizing an objective function describing the difference between 
observed and simulated conditions. These procedures generally provide the most structured and 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-129 November 2004 
thorough means of calibrating a model, and, frequently, they provide useful additional 
information regarding model sensitivity to parameters and other useful statistical measures. 
Consequently, an automated optimization procedure is used to calibrate the SZ site-scale flow 
model. However, manual adjustments to the calibration are also performed to ensure an accurate 
representation of fluxes in the low-head gradient portion of Fortymile Wash in the numerical 
model. 
Discussed below are the criteria used to guide calibration, optimization procedures used during 
calibration, those model outputs for which the difference between predicted and observed values 
were minimized (calibration targets) during calibration, and those parameters that were 
optimized during calibration. 
6.6.1.1 Calibration Criteria 
Proper calibration of the SZ site-scale flow model requires consideration of the full range of 
available data, which include field data for water levels and hydraulic heads, permeability data 
from field and laboratory tests, locations of known faults and other geologic data, and 
hydrochemical data. Opinions expressed during the expert elicitation process (CRWMS M&O 
1998 [DIRS 100353]) also must be considered. The goal during development of the SZ 
site-scale flow model was to deliver to performance assessment a model that is realistic where 
data exist and is conservative where data are lacking. 
6.6.1.2 Parameter Optimization Procedure 
Calibration of the SZ site-scale flow model was accomplished with the groundwater flow, heat, 
and transport computer code, FEHM (Zyvoloski et al. 1997 [DIRS 100615]) and commercial 
parameter estimation code PEST. PEST is a Levenberg-Marquardt (LM)-based optimization 
algorithm. The LM package is a well-established algorithm (Press et al. 1992 [DIRS 103316], 
pp. 678 to 683), very robust, and widely applicable. It will search for the minima of a 
multidimensional function. In this case, the function is the sum-of-squares difference (SSD) 
between a set of observations (the heads in 114 wells in the Yucca Mountain region plus 
side-boundary fluxes from the regional flow model) and the solution to the partial differential 
equation that describes SZ flow at Yucca Mountain. PEST computes the derivatives of the SSD 
function with respect to the various parameters. As discussed below in Section 6.6.1.3, those 
parameters optimized during calibration are the intrinsic permeability of each of the various 
hydrogeologic units and the permeability multipliers for some of the hydrogeologic features 
established in the model. An initial estimate or guess for each unknown parameter is specified at 
the beginning of the fitting process: 
1. FEHM computes the resulting heads for the initial estimate of parameters. 
2. The results are returned to the PEST code. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-130 November 2004 
3. Through a series of FEHM simulations with perturbations in the parameters, the 
LM package of PEST computes the derivative of the SSD function with respect to 
each of the parameters. 
4. The LM package of PEST then determines the amount to change each parameters 
current value to improve the fit to the data. It does this through a mathematical 
process that combines gradient information and second derivative (approximated) 
information. 
This process is repeated until the fit to data is within a prescribed tolerance or until no further 
improvement is possible. This coupling between PEST and FEHM allows any variable in 
FEHM to be considered as a fitting parameter, if desired, whether a flow-related or 
transport-related parameter. PEST will find local minima of the target function. To enable the 
PEST code to search for the global minimum, a procedure is attached to the code that carries out 
a simulated annealing process, which allows the PEST code to move from one local minimum to 
another, better local minimum. This process is repeated until no further improvement occurs. 
The simulated annealing process (Press et al. 1992 [DIRS 103316], pp. 436 to 448) is simple in 
principle. The approach is to reject an improved solution occasionally, move to a new location 
in parameter space, and continue the search. Theory indicates that this will eventually find the 
global or a near-global minimum. In the Yucca Mountain case, the procedure involves resetting 
the value of the LM step-size parameter after each local minimum is found. 
In addition to the PEST optimization described above, several manual adjustments were made to 
the model. These were made to improve the model in ways that were not possible during the 
PEST run. The most important adjustment was to ensure that the specific discharge near Yucca 
Mountain was realistic with respect to the estimates given by the SZ expert elicitation panel 
(CRWMS M&O 1998 [DIRS 100353]). Because the specific discharge was calculated with the 
particle-tracking feature of FEHM after the flow calculations were performed, this adjustment 
could not be incorporated easily in the PEST optimization. The specific discharge was adjusted 
by changing the permeability of the Bullfrog unit. Because of the large permeability of that unit, 
the specific discharge could be manipulated by changing the units permeability without 
adversely affecting the heads in the low-gradient area near Yucca Mountain. Adjustments also 
were made to the permeability in the lower Fortymile Wash area so water levels in the 
NC-EWDP-2D and Washburn wells in lower Fortymile Wash would be more consistent with 
those in the upper Fortymile Wash area, thus preserving the observed head gradient. These well 
locations will be discussed in Section 6.6.1.3. Adjustments to the permeability of the alluvial 
uncertainty zone and the permeability of the valley-fill aquifer also were made to better match 
eastern boundary fluxes of the regional model. 
Although the SZ model was calibrated with the application of the PEST code, the final product 
(a suite of FEHM files) does not include any PEST files. Thus, the SZ site-scale flow model 
may be used for performance assessment or other purposes without the inclusion of the PEST 
executable code or related files. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-131 November 2004 
6.6.1.3 Calibration Targets 
The SZ site-scale flow model was calibrated to achieve a minimal difference between observed 
water levels and predicted water levels, as well as between fluxes along specific boundary 
segments predicted by the regional model and the SZ site-scale model. For calibration targets, 
114 water level and head measurements were used. This was the complete set of wells available 
at the time of calibration. The measurements (DTN: GS000508312332.001 [DIRS 149947]) 
represent water levels and deeper head measurements. The deeper measurements represent 
average values over open or packed-off intervals, and the coordinates of the observations 
represent midpoints of the interval. The calibration targets also represent steady-state values. 
Where pumping is taking place, as in the Amargosa Valley, current water levels are used. When 
comparing simulated water levels to target water levels, the model represents water levels at the 
target locations by assigning the target head value to the nearest gridblock that is in the same 
hydrostratigraphic unit as the measurement. 
During the calibration process, emphasis was given to minimizing the difference between 
observed and simulated water levels at selected target locations based on probable flow 
pathways. This was accomplished by multiplying the squared differences at that location by a 
weighting factor. A weighting factor of 1 (i.e., standard importance) normally was applied to 
calibration targets. However, a preferential weighting factor (20) was applied to approximately 
30 calibration targets in the low-gradient region to the south and east of Yucca Mountain. These 
calibration targets were given high weighting, because they are in the likely groundwater 
pathway leaving the repository site and because small changes in head in this area could produce 
a large effect on the flow direction. Calibration targets north of Yucca Mountain are given a low 
weighting (0.05, i.e., little importance). The five wells in this category are given low weights 
primarily because of the possibility of perching and the attendant uncertainty in waterlevel 
measurements in this region. For the base case model, the moderate gradient wells or those wells 
that provide a transition between the high and low gradients proved to be relatively unimportant. 
The east-west barrier incorporated in the base case model to establish the LHG was the primary 
reason for this behavior. Other ACMs of the LHG without the east-west barrier were more 
sensitive to the moderate gradient wells and additional parameters were required for these 
models. The head measurement in the carbonate aquifer UE-25 (p #1) was given a preferential 
weighting factor (5) because of the importance of this calibration target for reproducing an 
upward gradient in the calibrated model. The inclusion of an upward gradient within the 
calibrated SZ site-scale flow model is considered to be important for generating a realistic model 
because an upward gradient tends to force flow along shallower path lines as indicated by 
geochemical data. A complete listing of all target waterlevel values, target locations, and the 
weighting applied to each target is provided in Table 6-18. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-132 November 2004 
Table 6-18. Comparison of Observed Weighting of Hydraulic Heads from the SZ Site-Scale Flow Model 
and Model Computed Head Data 
Site 
Name 
Fig. 
6-40 
Node 
Number 
x (UTM) 
(m) 
y (UTM) 
(m) 
z 
(elevation) 
(m) 
Measured 
Water Level 
Head Data* 
(m) 
Modeled 
Head) Weight 
UE-29 a #2 1 121034 555753 4088351 990.8 1187.7 1165.98 0.05 
GEXA Well 4 2 69302 534069 4086110 859.2 1009.0 1017.91 0.05 
UE-25 WT#6 3 120881 549352 4083103 983.2 1034.6 945.38 0.05 
USW G-2 4 84692 548143 4082542 371.5 1020.2 933.91 0.05 
UE-25 WT #16 5 117338 551146 4081234 714.1 738.3 734.62 1 
USW UZ-14 6 113564 548032 4080260 793.4 779.0 735.00 1 
UE-25 WT #18 7 117980 549468 4080238 722.1 730.8 734.78 20 
USW G-1 8 81935 548306 4080016 125.7 754.2 735.11 1 
UE-25 a #3 9 39729 561084 4079697 681.4 748.3 799.00 1 
UE-25 WT #4 10 117286 550439 4079412 709 730.8 734.57 20 
UE-25 WT #15 11 116632 554034 4078694 698.7 729.2 733.98 20 
USW G-4 12 103508 548933 4078602 542.2 730.6 734.61 20 
UE-25 a #1 13 109866 549925 4078330 584 731.0 734.47 1 
UE-25 WT #14 14 127094 552630 4077330 703.6 729.7 733.90 20 
USW WT-2 15 112088 548595 4077028 702 730.6 734.29 20 
UE-25 c #1 16 102578 550955 4075933 473.2 730.2 734.03 20 
UE-25 c #3 17 102578 550930 4075902 474.3 730.2 734.03 20 
UE-25 c #2 18 109378 550955 4075871 553.2 730.2 734.02 20 
UE-25 WT #13 19 127059 553730 4075827 703.8 729.1 733.47 20 
USW WT-7 20 118658 546151 4075474 740.9 775.8 768.13 1 
USW WT-1 21 112500 549152 4074967 708.4 730.4 733.97 20 
USW G-3 22 83665 547543 4074619 318.1 730.5 735.06 20 
UE-25 J-13 23 101936 554017 4073517 354.8 728.4 732.87 20 
USW WT-10 24 129857 545964 4073378 734.2 776.0 781.49 1 
UE-25 WT #17 25 112470 549905 4073307 705.4 729.7 733.69 20 
USW VH-2 26 122026 537738 4073214 282.8 810.4 794.36 1 
UE-25 WT #3 27 106625 552090 4072550 705.8 729.6 733.20 20 
USW VH-1 28 123007 539976 4071714 490.5 779.4 783.69 1 
UE-25 WT #12 29 116452 550168 4070659 702.6 729.5 733.02 20 
USW WT-11 30 116439 547542 4070428 691.9 730.7 733.80 20 
UE-25 J-12 31 110744 554444 4068774 659.6 727.9 731.60 20 
UE-25 JF #3 32 105329 554498 4067974 662.7 727.8 731.32 20 
Cind-R-Lite 
Well 
33 127537 544027 4059809 710.2 729.8 737.46 20 
Ben 
Bossingham 
34 126439 553704 4056228 697.4 718.4 714.91 1 
Fred Cobb 35 139338 553808 4055459 675.6 702.8 713.17 1 
Bob Whellock 36 139338 553883 4055398 682 704.1 713.17 1 
Louise 
Pereidra 
37 139875 554131 4055399 698 705.6 713.71 1 
Joe Richards 38 139338 554008 4055337 679.3 701.6 713.17 1 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-133 November 2004 
Table 6-18. Comparison of Observed Weighting of Hydraulic Heads from the SZ Site-Scale Flow 
Model and Model Computed Head Data (Continued) 
Site 
Name 
Fig. 
6-40 
Node 
Number 
x (UTM) 
(m) 
y (UTM) 
(m) 
z 
(elevation) 
(m) 
Measured 
Water Level 
Head Data* 
(m) 
Modeled 
Head) Weight 
NDOT Well 39 139338 553685 4055242 682.1 705.4 713.17 1 
James H. 
Shaw 
40 138458 549863 4054911 664.3 706.7 707.18 1 
Airport Well 41 137742 552818 4054929 636.5 705.3 711.26 1 
TW-5 42 39571 562604 4054686 688.7 725.1 726.67 1 
Richard 
Washburn 
43 138403 549746 4053647 669.9 707.7 705.75 1 
Richard 
Washburn 
44 139149 549679 4052322 675.3 704.4 703.72 1 
Nye County 
Develop. Co. 
45 137506 543481 4050069 638.6 694.3 696.59 1 
Fred 
Wooldridge 
46 138950 536350 4050006 673.8 691.9 688.06 1 
Fred J. Keefe 47 138957 540673 4049994 676.7 694.3 696.09 1 
Leslie Nickels 48 138146 541518 4049937 654.7 694.3 696.30 1 
L. Mason 49 67776 553471 4049848 699.2 722.1 711.61 1 
Unknown 50 138123 545596 4049403 667.6 697.8 695.93 1 
Davidson Well 51 138915 536552 4049329 672 690.1 688.07 1 
Eugene J. 
Mankinen 
52 67243 538889 4049000 678.6 707.4 691.82 1 
Donald O. 
Heath 
53 138086 542194 4048892 651.6 694.1 694.47 1 
Elvis Kelley 54 138883 536903 4048621 685.1 691.0 688.16 1 
Manuel 
Rodela 
55 138899 546718 4048669 686.7 693.6 695.25 1 
Charles C. 
DeFir Jr. 
56 67220 538196 4048442 685.7 706.9 691.09 1 
William R. 
Monroe 
57 138051 540035 4048450 669.5 693.7 694.78 1 
DeFir Well 58 138854 536655 4048405 671.1 690.2 688.21 1 
Edwin H. 
Mankinen 
59 138053 540608 4048083 662.8 695.2 694.38 1 
Bill Strickland 60 138820 534967 4047966 677 689.2 687.22 1 
M. Meese 61 138036 547120 4047963 664.6 686.4 693.44 1 
Theo E. 
Selbach 
62 136554 547941 4047782 673.3 696.2 693.97 1 
C.L. Caldwell 63 66654 537727 4047670 654.5 691.4 690.70 1 
Leonard 
Siegel 
64 138042 552390 4047685 667.2 709.0 703.69 1 
James K. 
Pierce 
65 138025 541778 4047596 664 690.4 693.40 1 
James K. 
Pierce 
66 138828 541381 4047563 677.1 705.6 693.63 1 
Cooks West 
Well 
67 136594 553609 4047631 690.2 720.1 712.20 1 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-134 November 2004 
Table 6-18. Comparison of Observed Weighting of Hydraulic Heads from the SZ Site-Scale Flow 
Model and Model Computed Head Data (Continued) 
Site 
Name 
Fig. 
6-40 
Node 
Number 
x (UTM) 
(m) 
y (UTM) 
(m) 
z 
(elevation) 
(m) 
Measured 
Water Level 
Head Data* 
(m) 
Modeled 
Head) Weight 
Cooks East 
Well 
68 136594 554006 4047633 693.4 718.9 712.20 1 
Nye County 
Land Co. 
69 136550 548466 4047261 715.4 690.1 693.27 1 
Amargosa 
Town 
Complex 
70 136512 548492 4047077 668.3 688.8 693.27 1 
Nye County 
Develop. Co. 
71 137090 550431 4047057 615.4 691.2 694.88 1 
Lewis C. Cook 72 136591 553612 4047076 702.5 717.4 714.00 1 
Lewis C. Cook 73 136553 553687 4047077 688.7 714.8 714.01 1 
Amargosa 
Valley Water 
74 136545 548393 4046953 673.9 701.3 691.81 1 
Earl N. 
Selbach 
75 67149 539147 4046844 672.1 696.5 694.05 1 
Lewis N. 
Dansby 
76 137961 539968 4046817 664.7 694.2 695.22 1 
Edwin H. 
Mankinen 
77 138767 540788 4046821 686.2 694.0 693.64 1 
Willard Johns 78 138786 552097 4046882 678.9 699.5 708.82 1 
USW H-1 
tube 1 
79 118456 548727 4079926 495.5 785.5 830.84 1 
USW H-1 
tube 2 
80 91032 548727 4079926 193 736.0 734.79 1 
USW H-1 
tube 3 
81 103512 548727 4079926 562.5 730.6 734.74 20 
USW H-1 
tube 4 
82 111633 548727 4079926 680.5 730.8 734.76 20 
USW H-5 
upper 
83 106331 547668 4078841 704.2 775.5 734.76 1 
USW H-5 
lower 
84 94198 547668 4078841 446.4 775.6 734.77 1 
UE-25 b #1 
lower 
85 81208 549949 4078423 8.8 729.7 735.63 20 
UE-25 b #1 
upper 
86 102018 549949 4078423 366.2 730.6 734.45 20 
USW H-6 
upper 
87 105485 546188 4077816 662.9 776.0 764.14 1 
USW H-6 
lower 
88 91691 546188 4077816 315.8 775.9 763.99 1 
USW H-4 
upper 
89 93378 549188 4077309 395.5 730.4 734.36 20 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-135 November 2004 
Table 6-18. Comparison of Observed Weighting of Hydraulic Heads from the SZ Site-Scale Flow 
Model and Model Computed Head Data (Continued) 
Site 
Name 
Fig. 
6-40 
Node 
Number 
x (UTM) 
(m) 
y (UTM) 
(m) 
z 
(elevation) 
(m) 
Measured 
Water Level 
Head Data* 
(m) 
Modeled 
Head) Weight 
USW H-4 
lower 
90 81182 549188 4077309 45 730.5 735.20 20 
USW H-3 
upper 
91 96228 547562 4075759 576.9 731.5 734.59 20 
USW H-3 
lower 
92 84647 547562 4075759 343.2 755.9 734.62 1 
UE-25 p #1 
(Lwr Intrvl) 
93 28770 551501 4075659 410.3 752.4 739.73 5 
USW SD-7 95 104836 548384 4076499 637.7 727.6 734.24 20 
USW SD-9 96 111629 548550 4079256 678.3 731.1 734.75 20 
USW SD-12 97 106315 548492 4077415 696.7 730.0 734.42 20 
USW WT-24 98 50635 548697 4081909 734.8 840.1 742.01 1 
NC-EWDP- 
1DX, shallow 
99 84963 536768 4062502 413.5 786.8 763.89 1 
NC-EWDP-1S 
probe 1 
100 113410 536771 4062498 747.8 787.1 773.29 1 
NC-EWDP-2D 101 63142 547744 4057164 507.2 706.1 709.21 1 
NC-EWDP-3D 102 84914 541273 4059444 376.7 718.3 703.75 1 
NC-EWDP-3S 
probe 2 
103 106390 541269 4059445 719.1 719.8 702.40 1 
NC-EWDP- 
5SB 
104 103618 555676 4058229 603.9 723.6 717.45 1 
NC-EWDP- 
9SX probe 2 
105 89328 539039 4061004 721.2 767.3 732.42 1 
NCWashburn-
1X 
106 104959 551465 4057563 668.8 714.6 714.01 1 
UE-25 J-11 107 125874 563799 4071058 687.2 732.2 731.57 20 
BGMW-11 108 67494 534386 4062600 673.4 715.9 724.53 1 
Richard 
Washburn 
109 139739 549529 4052567 739.9 704.0 703.85 1 
L. Cook 110 138814 551348 4047432 704.1 713.2 699.01 1 
Unknown 111 67200 549532 4047668 691.8 689.5 695.01 1 
Amargosa 
Water 
112 138840 547420 4047594 714.3 690.4 693.44 1 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-136 November 2004 
Table 6-18. Comparison of Observed Weighting of Hydraulic Heads from the SZ Site-Scale Flow 
Model and Model Computed Head Data (Continued) 
Site 
Name 
Fig. 
6-40 
Node 
Number 
x (UTM) 
(m) 
y (UTM) 
(m) 
z 
(elevation) 
(m) 
Measured 
Water Level 
Head Data* 
(m) 
Modeled 
Head) Weight 
Lewis C. Cook 113 68127 554329 4047666 735.5 715.7 713.64 1 
Unknown 114 67243 538989 4048877 710.1 690.8 691.82 1 
USW UZ-N91 115 121579 555680 4088196 1180.6 1186.7 1165.80 0.05 
Source: DTN: GS010908312332.002 [DIRS 163555]. 
Output DTN: LA0304TM831231.002. 
*Head data refers to the observed mean water-level altitude (m). UTM = Universal Transverse Mercator 
NOTE: The Figure. 6-40 label in the second column of the table refers to the well numbers given in Figure 6-40. 
The information on site name, UTM coordinates easting and northing, and measured heads is from 
DTN: GS010908312332.002 [DIRS 163555]. The measured heads in Table 6-18 correspond to the 
average water table altitude data in DTN: GS010908312332.002 [DIRS 163555]. Mean water-level 
altitudes were calculated as time-averages over the period of available measurements and were rounded 
to the nearest tenth of a meter. 
The elevation Z shown in Table 6-18 is from DTN: LA0304TM831231.002 [DIRS 163788]. These data 
are stored in file pest_new.macro. This file provides elevation per each well along with UTM coordinates. 
The model heads shown in Table 6-18 are from DTN: LA0304TM831231.002 [DIRS 163788]. The 
calibrated heads are stored in file 02_calib.pest. This file provides initial, intermediate, and final values of 
all the calibrated parameters. The final heads are located at the end of this file and correspond to the 
simulation time equal to 0.36525E+17 days. Each well is represented by specific node. The relationship 
between the wells and the nodes is provided in Table 6-18. There are 119 nodes in the output file. The 
last 4 nodes are not shown in Table 6-18 since they do not represent any of the observation wells. These 
4 points were added to the calibration targets to condition the results, so that the heads would stay 
reasonable (in agreement with the potentiometric surface defined) in the areas with no data. The heads 
in Table 6-18 can be obtained from the corresponding heads shown in the output file by subtracting 5000 
from the later ones. For example, the well UE-25 WT#6, shown in Figure 6-40 by number 3 is assigned 
to node number 120881. The head in this node is in the output file 5945.38. The head shown for this 
well in Table 6-18 is 5945.38 5000 = 945.38 m. 
Location 94, which is well USW SD-6 is not used. This reduces the number of observation points to 114. 
In addition to water levels, fluxes around certain boundary segments were used as calibration 
targets. Fluxes from all boundary segments on the eastern and northern boundaries of the SZ 
site-scale flow model domain were used as calibration targets during parameter optimization. 
Fluxes from the five western boundary segments were not used during parameter optimization 
(see Section 6.6.2.2, Table 6-20a). Preliminary calibration runs indicated that it was difficult to 
match the fluxes along these segments predicted by the SZ site-scale flow model with those 
predicted by the DVRFS model (see Section 6.6.2.2, Table 6-20a). This difficulty largely was a 
result of the different HFMs used in the site-scale and regional-scale flow models. The goal of 
ensuring that the total flux through the SZ site-scale flow model domain is close to that predicted 
by the regional-scale model was achieved by not forcing a close match along those boundary 
segments for which the rock types (because of differences in the grid resolution and the HFMs) 
were different in the two models. Thus, a weighting scheme was used with the target fluxes. 
Zero weight was applied to the western boundary segments and weights between one and two 
were used for the eastern and northern segments. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-137 November 2004 
6.6.1.4 Calibration Parameters 
Calibration of permeability was optimized during calibration of the SZ site-scale flow model. 
The model formulation and the FEHM code allow for the specification of a permeability value at 
each node. However, there are not sufficient water level and permeability data to warrant 
identifying a specific value of permeability for each individual node during calibration. 
Consequently, sets of nodes are grouped into specific permeability zones based on similar 
permeability characteristics. A single permeability value is assigned to each zone. These zonal 
values of permeability serve as the parameters that are optimized during model calibration. 
Permeability zones were created for hydrogeologic units identified in the HFM-19 conceptual 
model and for specific hydrogeologic features. With the exception of the basal unit that serves 
as a lower boundary for the model, a permeability zone was established for each hydrogeologic 
unit. All of the nodes within a specific hydrogeologic unit were assigned to that permeability 
zone unless they are included in one of the permeability zones established for specific 
hydrogeologic features. The zone sizes were fixed, largely based on the HFM-19. Some of the 
uncertainty associated with geologic contacts is discussed in Section 6.8.5.1. 
For permeability, vertical anisotropy is assigned a value of 10:1 (horizontal to vertical) in the 
volcanic and valley-fill units in the SZ site-scale flow model. Relatively lower permeability in 
the vertical direction may occur in stratified media, and the ratio of 10:1 is in the generally 
accepted range (CRWMS M&O 1998 [DIRS 100353], Table 3-2). Furthermore, the relatively 
high vertical gradient observed in well UE-25p#1 suggests that vertical permeability is lower 
than horizontal permeability. Well NC-EWDP-2D also exhibited a vertical gradient. The 
uncertainty associated with the vertical anisotropy is discussed in Section 6.8.3.1. 
Specific hydrogeologic features that were thought to potentially impact groundwater flow also 
were classified as permeability zones. The permeability variable or permeability multiplication 
factor used for a specific feature was assigned to all of the nodes within that feature. The 
hydrogeologic features for which special permeability zones were established are primarily 
faults, fault zones, and areas of chemical alteration (Section 6.5.2). As previously discussed, 
these features are distinct from the subhorizontal hydrogeologic units identified in the HFM-19 
conceptual model. Each of the identified hydrogeologic features includes multiple geologic 
formations and represents zones of altered permeability within the individual formations. 
Twenty-seven permeability zones were established for model calibration. In addition, 
permeability multipliers were assigned to four zones containing geologic features that penetrate a 
number of hydrogeologic units. The permeability multipliers were used to modify the 
permeability values assigned to the hydrogeologic units in the area of the geologic features. 
Although the permeability parameter or multiplier values for most zones were optimized during 
calibration, permeability for the upper carbonate aquifer was assigned a constant value because 
sensitivity analyses indicate that the model is not sensitive to this parameter value. 
The parameters used in the calibration of the SZ site-scale flow model are a combination of 
permeabilities of hydrogeologic units, permeabilities of faults and other features, and 
permeability multipliers of faults and features. Permeabilities of the 18 hydrogeologic units were 
chosen as calibration parameters because of the importance of the parameter in the flow system 
and each of the units was identified in the HFM-19 conceptual model. The parameters that 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-138 November 2004 
represent these features were added because they were identified as important structural features 
(e.g., the Solitario Canyon fault), were in the regional-scale model (e.g., the Spotted Range-Mine 
Mountain zone), or were necessary for some conceptual feature, such as the LHG north of Yucca 
Mountain (east-west barrier). The number of parameters represents a computationally tractable 
set. 
Upper and lower bounds were placed on each permeability variable during parameter 
optimization. The upper and lower bounds for the permeabilities and permeability multipliers 
were chosen to reflect maximum and minimum field values (permeability) or a reasonably 
realistic range of values (permeability multipliers) (See Sections 7.2.2.4.1 to 7.2.2.4.4). For 
example, when the multiplier represents flow in the plane of a fault, the multiplier is allowed to 
take on values between 1 and 100; when the multiplier represents geochemical alteration, the 
multiplier is allowed to take values between 0.00001 and 0.50000. The upper bounds for 
permeability for faults were generally higher than the hydrostratigraphic unit where the fault was 
situated. The final calibrated values of the parameters are not sensitive to initial parameter 
values within the range specified, thus giving confidence that the calibration values are unique 
within the specified bounds of permeability. 
A list of permeability zones, including the parameter type assigned to each zone, the upper and 
low bounds specified for the parameter, and an identification of the parameters optimized during 
calibration, are provided in Table 6-19. 
Table 6-19. Calibration Parameters Used in the SZ Site-Scale Flow Model 
Parameter 
Name 
Geologic Unit 
or Feature 
Calibrated 
Value 
Parameter 
Type 
Minimum 
Value 
Maximum 
Value 
gran Granitic Confining Unit 1.96 x 1016 Permeability 1.00 x 1017 1.00 x 1014 
lcla Lower Clastic Confining Unit 1.00 x 1016 Permeability 1.00 x 1016 1.00 x 1014 
lca2 Lower Carbonate Aquifer 5.00 x 1014 Permeability 5.00 x 1014 1.00 x 1012 
ucla Upper Clastic Confining Unit 1.00 x 1016 Permeability 1.00 x 1016 1.00 x 1014 
lca1 Lower Carbonate Aquifer Thrust 1.00 x 1014 Permeability 1.00 x 1014 1.00 x 1012 
ucar Upper Carbonate Aquifer 4.08 x 1014 Permeability (fixed) 4.08 x 1014 4.08 x 1014 
udif Undifferentiated Valley Fill 5.00 x 1015 Permeability 5.00 x 1015 1.00 x 1012 
ovoc Older Volcanic Confining Unit 2.00 x 1016 Permeability 2.00 x 1016 1.00 x 1011 
ovoa Older Volcanic Aquifer 5.00 x 1016 Permeability 3.00 x 1016 1.00 x 1012 
lvoc Lower Volcanic Confining Unit 2.00 x 1015 Permeability 1.00 x 1015 1.00 x 1011 
tram Crater Flat-Tram 2.36 x 1013 Permeability 1.00 x 1013 1.00 x 1011 
bull Crater Flat-Bullfrog 1.54 x 1011 Permeability 1.00 x 1013 8.00 x 1011 
prow Crater Flat-Prow Pass 8.00 x 1012 Permeability 1.00 x 1013 5.00 x 1011 
uvoc Upper Volcanic Confining Unit 5.00 x 1014 Permeability 4.00 x 1014 1.00 x 1012 
uvoa Upper Volcanic Aquifer 8.00 x 1014 Permeability 8.00 x 1014 1.00 x 1011 
lava Lava Flow Aquifer 1.00 x 1012 Permeability 1.00 x 1016 2.00 x 1012 
lime Limestone Aquifer 1.00 x 1012 Permeability 1.00 x 1015 1.00 x 1011 
vala Valley Fill Aquifer 5.00 x 1012 Permeability 1.00 x 1013 8.00 x 1012 
ewba East-West Barrier 1.05 x 1018 Permeability 1.00 x 1018 1.00 x 1015 
nsba Solitario Canyon Fault 1.00 x 1018 Permeability 1.00 x 1018 1.00 x 1015 
fpb1 Fortymile Wash Fault 10 Multiplier 2 100 
fpb2 Spotted Range-Mine Mountain 
Zone 
11.7789 Multiplier 1 70 
fpb3 Northern Low Permeability 
Zone 
7.11 x 102 Multiplier 1.00 x 105 0.5 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-139 November 2004 
Table 6-19. Calibration Parameters Used in the SZ Site-Scale Flow Model (Continued) 
Parameter 
Name 
Geologic Unit 
or Feature 
Calibrated 
Value 
Parameter 
Type 
Minimum 
Value 
Maximum 
Value 
fpb4 Imbricate Fault Zone 1 Multiplier 1 100 
cffz Crater Flat Fault 5.00 x 1014 Permeability 1.00 x 1015 5.00 x 1013 
allu Alluvial Uncertainty Zone 3.20 x 1012 Permeability 1.00 x 1013 1.00 x 1011 
wash Lower Fortymile Wash Zone 5.00 x 1012 Permeability 1.00 x 1014 8.00 x 1012 
Output DTN: LA0304TM831231.002. Minimum and Maximum values are indirect input. 
NOTE: Permeability listed is the geometric mean and is in the units of m2. The water levels predicted by the 
calibrated SZ site-scale flow model along with the observed water level at each of the calibration target 
locations are presented in Table 6-18. 
6.6.2 Calibration Results 
6.6.2.1 Water Levels 
The water levels predicted by the calibrated SZ site-scale flow model along with the observed 
water level at each of the calibration target locations are presented in Table 6-19. The location of 
each target observation well is shown in Figure 6-40. The calibration targets (water levels) are 
from DTN: GS000508312332.001 [DIRS 149947] and updated in DTN: GS010908312332.002 
[DIRS 163555]. The waterlevel data from Faunt (2001 [DIRS 154625], Attachment I) were 
used in the development of the site-scale flow model. The potentiometric surface (Faunt 2001 
[DIRS 154625], Figure 1-2) as provided in DTN: GS000508312332.001 [DIRS 149947] was 
used to truncate the top of the flow model grid and provide the water levels supplied as boundary 
conditions around the perimeter of the model. The water levels presented by Faunt (2001 
[DIRS 154625], Attachment I) as provided in DTN: GS000508312332.001 [DIRS 149947] were 
specified as waterlevel target values for calibration. During the process of calibration, 
additional waterlevel data from Tucci (2004 DIRS 168473], Attachment I) became available 
and were used to supplement the data from Faunt. Specifically, an additional waterlevel 
location, USW WT-24, was added and the eight waterlevel locations corresponding to the 
NC-EWDP) in Faunt (2001 [DIRS 154625]) were replaced by equivalent locations from Tucci 
(2004 [DIRS 168473]). The remaining 15 Nye County locations presented by Tucci (2004 
[DIRS 168473]) were not added to the calibration targets, but rather were saved and used for 
validation (see Table 7-2). Of the final 114 waterlevel calibration targets presented Table 6-18, 
105 values were obtained from DTN: GS000508312332.001 [DIRS 149947] and nine values 
were obtained from DTN: GS010908312332.002 [DIRS 163555]. The calibration targets are 
discussed in Section 6.6.1.3. The distribution of residuals, along with the measured and 
simulated waterlevel surfaces, resulting from the calibrated model is provided in Figure 6-41. 
The actual water levels (not the interpolated surface) in each well are used for comparison. In 
the more recent interpretations, such as DTN: GS010608312332.001 ([DIRS 155307]), 
potentiometric surface map output from Water-Level Data Analysis for the Saturated Zone 
Site-Scale Flow and Transport Model (USGS 2001 [DIRS 157611]), the head contours have 
been smoothed in the area near wells WT-24 and G-2 to reflect perched conditions. The 
different interpretations of the water table surface, that is, whether or not wells WT-24 and G-2 
are perched, have little impact on the results. This is because those wells were given a low 
weight (owing to their suspect levels) and do not affect the calibration. Interestingly, the model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-140 November 2004 
consistently reports simulated levels in WT-24 and G-2 that are closer to the perched 
interpretations than the original high water table values. 
A weighting scheme was used in conjunction with the PEST code to focus the calibration in 
areas where the confidence in the data was high (i.e., the low gradient area) or importance to the 
TSPA calculations was great (i.e., along the flow path). A low weighting on a target value will 
cause PEST to essentially ignore the value, and high value will cause PEST to respect the target 
value at the expense of other observations. 
The calibrated SZ site-scale flow model has a sum-squared, weighted residual of approximately 
27,600, which translates into approximately a 16-m (weighted) residual for each observation. 
Without weighting, the sum-squared residual is approximately 90,000, which corresponds to the 
approximately 30-m average residual for each observation. Compared to the overall head drop 
of approximately 500 m in the SZ site-scale flow model, the 30-m average residual amounts to a 
6 percent error. 
As can be seen in Figure 6-41, the largest head residuals (~80 m) are in the northern part of the 
model in the high-head gradient area near the east-west barrier. In the figure, a negative residual 
means that the calibrated value was lower than the target data. These head values are largely the 
result of the low weighting factor of (0.05) and the uncertainty in these measurements, possibly 
due to perched conditions. The next highest group of head residuals borders the east-west barrier 
and the Solitario Canyon fault. These residuals (~50 m) are most likely the result of 500-m grid 
blocks not being able to resolve the 780-m to 730-m drop in head in the very short distance just 
east of the above-mentioned features. There may well be additional complicating factors such as 
the changing character in the Solitario Canyon fault along its north-south transect. The fault is 
modeled as a barrier with only one calibration parameter. This may be inadequate to represent 
the behavior locally of such a long feature. For example, well H-5, about 1,000 m from the 
Solitario Canyon fault, has discrepancy between measured and simulated heads of 41 m. The 
measured head for this well (775 m), located on the east side of the fault, is closer to measured 
head values on the west side of the fault. Because the majority of wells on the east side are 
approximately 735 m, the simulated head for H-5 was close to that value. Luckey et al. (1996 
[DIRS 100465], p. 25) discuss potential causes for the high-head measurements at H-5 located 
just to the east of the Solitario Canyon fault. When the predicted and the observed waterlevel 
surfaces were compared, it should be noted that both water table surfaces are contoured and that 
the data distribution for both surfaces is not uniform. Evident in the comparison is the 
low-gradient region in the Fortymile Wash region, the high-gradient region north of Yucca 
Mountain, and the flow disruption caused by the Solitario Canyon fault. These results indicate 
that the model adequately represents the current water table near Yucca Mountain. 
The recharge map used in the calibration process is described in Recharge and Lateral 
Groundwater Flow Boundary Conditions for the Saturated Zone Site-Scale Flow and Transport 
Model (BSC 2004 [DIRS 170015], Section 6.2). During performance assessment (TSPA-SR) 
calculations (CRWMS M&O 2000 [DIRS 139440]), a revised recharge map was used than the 
one used here. The older map was used for calibration purposes, because it was the only map 
available at the time of calibration. The only differences are in the area of the model associated 
with the UZ model, and in that area, the changes were small. The complete details of the newer 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-141 November 2004 
recharge map are described in Input and Results of the Base Case Saturated Zone Flow and 
Transport Model for TSPA (CRWMS M&O 2000 [DIRS 139440]). 
The important aspect to be addressed in this report is the effect of the newer recharge map on the 
calibrated SZ site-scale flow model. The differences are given in Table 6-18 with tenths of a 
meter difference at most. Thus, it is appropriate for the TSPA to use either recharge map. 
5350 5400 5450 5500 5550 5600 
UTM Easting 
( ) 
40500 
40550 
40600 
40650 
40700 
40750 
40800 
40850 
40900 
U T 
M 
N ort 
hi 
n g ( 
m ) 
1
115 
9 
11 
14 
19 
23 
27 
25 
24 
22 21 93 
17 20 
87 
88 
91 
94 
83
6 8 
98 
4 3 
5 
7 
10 
90
85 
13 
12 
96 
79 
80 
81 
82 
97
95 15 
2 
26 
28 
30 29 107 
31 
32 
108 100 
99 105 
102 
103 33 
101 106 
104 
42 40 
43 
109 44 
34
35 36 
37 38 
39 41 
49
113 67 
68 
72 73 
64 
78 
110 
71 
111 
69 70 
74 
62 
112 
61 
55 
50 
45 
53 
48 47 
66 65 
75 76 77 
59 
57 
52 114 
56 
63 
54 
58 
46 
51 
60 
DTN: GS010908312332.002 [DIRS 163555]. 
NOTE: Numbers in the figure refer to the well numbers also listed in the second column of Table 6-18; 
UTM = Universal Transverse Mercator 
Figure 6-40. Location of Observation Wells 
MDL-NBS-HS-000011 REV 02 6-142 November 2004 
Saturated Zone Site-Scale Flow Model 
Source: DTN: GS000508312332.001 [DIRS 149947], left panel; Output DTN: LA0304TM831231.002, right panel. 
NOTE: Symbols in right panel represent well locations; UTM = Universal Transverse Mercator 
Figure 6-41. Contour Plot of WaterLevel Data (Left Panel) and Simulated WaterLevel Data with Residual Heads (Right Panel) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-143 November 2004 
6.6.2.2 Comparing Fluxes Derived from the Regional Model with Fluxes Calculated 
from the Calibrated Model 
The SZ site-scale flow model describes a small part of the Death Valley regional groundwater 
flow system. By comparing the SZ site-scale flow model with the regional flow model, 
additional constraints can be applied to the SZ site-scale flow model. The comparison between 
the two models was also suggested by the Expert Elicitation Panel (CRWMS 1998 
[DIRS 100353]). The numerical model of the regional flow system models a closed system and 
contains data from spring discharges to help fix the water flux through the system (DAgnese et 
al. 1997 [DIRS 100131]). Thus, it is appropriate to compare the fluxes in the two models. 
The regional model uses a 1997 regional HFM, which is described by DAgnese et al. (1997 
[DIRS 100131]). The SZ site-scale flow model uses the HFM-19, which is described in 
Hydrogeologic Framework Model for the Saturated-Zone Site-Scale Flow and Transport Model 
(BSC 2004 [DIRS 170008]. 
In Section 6.6.1.4, the methodology for applying fixed-head boundary conditions on the sides of 
the SZ site-scale flow model was described. With fixed-head boundary conditions, the flux 
through the boundary is a function of the permeabilities. A comparison of fluxes derived from 
the regional model and fluxes derived from the calibrated site-scale flow model are shown in 
Table 6-20a. In this table, the zones with N in the label refer to the northern boundary, those 
with an E, the eastern boundary, and so on. The zones are depicted graphically in Figure 6-42. 
The comparison is reasonable on the northern and eastern boundaries. The northern boundary, 
for instance, has a total flux of 189 kg/s (6.0  106 m3/yr) across it in the regional model and 
169 kg/s (5.3  106 m3/yr) across it in the SZ calibrated model. As can be seen in Table 6-20a 
and Figure 6-42, the distribution is different, which is not unexpected because the regional and 
SZ calibrated models are based on different hydrogeologic models. The target calibration fluxes 
are a little different from those extracted from the regional model (Table 6-20b). Those 
differences did not affect the calibration results. Table 6-20b shows the fluxes extracted from a 
comparison of the 1997 regional model and 2001 regional model. The match was good on the 
eastern side of the model with the lower thrust area, E1. The other zones showed small flows in 
both models. The match between the two models was poor on the western boundary. The 
southern boundary flux, which is simply a sum of the other boundary fluxes plus the recharge, is 
also a good match. The difference in southern fluxes (shown as Zone S in Table 6-20a) is about 
21 percent. 
Several factors affect the flux match between the two models: the horizontal and vertical 
resolution, the hydrologic framework model, and the permeability distribution. The horizontal 
resolution of the site-scale flow model is nine times finer than the regional model (500-m versus 
1,500-m grid block size). The vertical resolution of the SZ site-scale flow model is an order of 
magnitude finer than the regional model (39 versus 3 layers). The increased resolution of the site 
scale means that fluxes calculated by the SZ site-scale flow model may depend more strongly on 
a few units than on the regional-scale model. This fact is important when considering that many 
of the unit permeabilities in the SZ site-scale flow model are constrained by field data. The 
HFM-19 used in the SZ site-scale flow model differs considerably from the 1997 regional HFM 
used in the 1997 DVRFS model, which is why the matching requirements for the fluxes were 
relaxed for the western boundary and the flux distribution is different on the northern boundary. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-144 November 2004 
The last factor affecting the flux distribution in the regional model is the use of permeability 
classes. In the regional model, permeabilities associated with specific units are not defined 
(DAgnese et al. 1997 [DIRS 100131]). Rather, the permeabilities are grouped into classes, 
which are assigned to a particular grid block based on the percentages of the rock types 
contained in the grid block. Thus, although the DVRFS model was based on a complex HFM, 
the actual model used only four permeability classes. That method of assigning permeabilities 
made it difficult to reproduce the distribution of fluxes on the side of the SZ site-scale flow 
model, if done on a unit-by-unit basis. In turn, this discrepancy makes it difficult to reproduce 
vertical flow or head gradients if they existed in the regional model because this would require a 
flux distribution on the lateral boundaries assigned by hydrogeologic unit. Never the less, the 
difference in the total flux across the southern boundary between the SZ site-scale flow model 
and the regional model is well within the range considered acceptable by the Expert Elicitation 
Panel (CRWMS M&O 1998 [DIRS 100353]). This water table is propagated through the 
distribution of specific discharge used in the transport abstraction. 
Table 6-20a. Comparison of Regional and Site-Scale Fluxes 
Regional Flux Site-Scale Flux Boundary 
Zone kg/s m3/yr kg/s m3/yr 
Calibration 
Target? 
N1 102 3.2  106 60.0 1.9  106 Yes 
N2 16.5 5.9  105 33.4 1.0  106 Yes 
N3 53.0 2.0  106 30.6 1.0  106 Yes 
N4 18.4 3.3  105 44.8 1.4  106 Yes 
W5 3.45 1.1  105 4.17 1.5  105 No 
W4 71 2.2  106 0.007 2.3  102 No 
W3 6.9 2.2  106 0.000008 0.2 No 
W2 2.73 8.6  104 0.00002 0.7 No 
W1 47.0 1.5  106 6.85 2.2  104 No 
E1 555. 1.8  107 554 1.7  107 Yes 
E2 5.46 1.7  105 3.53 1.1  105 Yes 
E3 2.65 8.3  104 16.5 5.2  105 Yes 
E4 3.07 3.7  104 16.8 5.3  105 Yes 
S 918 2.5  107 724 2.3  107 No 
Source: BSC 2004 [DIRS 170015], pp. 26-30; Output DTN: LA0304TM831231.002. 
NOTE: A negative value indicates flow into the model. Values were rounded to two or three 
significant digits. Target flux values for N2, N3, N4, and S are different from the DVRFS 
model. However; these differences did not affect the calibration results. 
6.6.2.3 Predicted Flow Paths 
The particle-tracking capability of FEHM was used to demonstrate flow paths predicted by the 
calibrated SZ site-scale flow model. One hundred particles were distributed uniformly over the 
area of the repository and allowed to migrate until they reached the model boundary 
(Figure 6-43). The pathways generally leave the repository and travel in a south-southeasterly 
direction to the 18-km compliance boundary. From the 18-km boundary to the end of the model, 
the flow paths trend to the south-southwest and generally follow Fortymile Wash. Most of the 
pathways pass through the designated Imbricate zone (Zone 91 of Figure 6-37). Some of the 
pathways follow fault zones along Fortymile Wash (Zones 57 and 58 of Figure 6-37). The 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-145 November 2004 
hydrogeologic units through which the flow leaving the repository layer passes consist of the 
Crater Flat group (Bullfrog, Tram, and Prow Pass) with most of the flow in the Bullfrog unit, the 
upper volcanic aquifer, the upper volcanic confining unit, the valley fill unit, and the 
undifferentiated valley-fill unit. Figure 6-43 shows a vertical cross section of the path lines. 
Evident in the figure is the shallow depth of the path lines, which is consistent with data 
supporting an upward head gradient. In Section 7, the fluid pathways are compared with those 
inferred from geochemical data. 
6.6.2.4 Specific Discharge 
Using the calibrated SZ site-scale flow model, specific discharge was estimated for a nominal 
fluid path leaving the repository area and traveling 0 to 5 km, 5 to 20 km, and 20 to 30 km (0, 3, 
12.5, and 18.6 miles). The specific discharge simulated by the SZ site-scale flow model for each 
segment of the flow path from the repository was determined using the median transport time 
(50th particle) for a group of particles released beneath the repository. By dividing the distance 
between the boundaries (shown in Figure 6-43) by the median transport time, values for specific 
discharge of 0.67 m/yr, 2.3 m/yr, and 2.5 m/yr (2.2, 7.5, and 8.2 ft/yr) were obtained, 
respectively, for the three segments of the flow path. The expert elicitation panel (CRWMS 
M&O 1998 [DIRS 100353], Figure 3-2e) estimated a median specific discharge of 0.71 m/yr 
(2.3 ft/yr) for the 5-km (3-mi) distance. Thus, good agreement is found between the specific 
discharge predicted by the calibrated SZ site-scale flow model and that estimated by the expert 
elicitation panel for this distance. The expert elicitation committee did not consider other travel 
distances. Mass balance error for all runs was zero. 
Table 6-20b Comparison of Fluxes at the Site-Scale Boundaries Predicted by the 1997 and 2001 
Regional Flow Models 
1997 
Regional Flux 
2001 
Regional Flux 
Boundary Zone (m3/yr)b kg/sa (m3/yr)b kg/sa 
N1 -3.2  106 -102 -6.9  106 -219 
N2 -5.9  105 -18.9 -1.8  106 -57.1 
N3 -2.0  106 -64.7 2.2  105 6.9 
N4 -3.3  105 -10.6 -4.3  105 -1.37 
Subtotal of North Boundary Fluxes -6.2  106 -196 -8.5  106 -271 
W5 1.1  105 3.45 6.6  106 210 
W4 -2.2  105 -71 -2.5  103 -0.08 
W3 -2.2  105 -6.9 -1.8  106 -56.1 
W2 8.6  104 2.73 -4.1  104 -1.31 
W1 -1.5  106 -48.0 -8.9  105 -28.4 
Subtotal of West Boundary Fluxes -3.7  106 -119 3.9  106 124 
E1 -1.8  107 -555 -2.2  106 -69.7 
E2 -1.7  105 -5.46 -3.2  102 -0.01 
E3 8.3  104 2.65 4.4  106 138.1 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-146 November 2004 
Table 6-20b. Comparison of Fluxes at the Site-Scale Boundaries Predicted by the 1997 and 
2001 Regional Flow Models (Continued) 
1997 
Regional Flux 
2001 
Regional Flux 
Boundary Zone (m3/yr)b kg/sa (m3/yr)b kg/sa 
E4 -9.7  104 -3.07 -4.8  104 -1.53 
Subtotal of East Boundary Fluxes -1.8  107 -561 -6.6  106 -209 
S 2.5  107 790 1.4  107 430 
NOTE: Negative values indicate flow into the model. Values were rounded to two or three significant 
digits. 
Source: aDTN: SN0407T0504404.002 [DIRS 170929], pp. 6-26 and 6-27. 
b Conversion factor: m3/yr = 
s 
kg 
yr
day 
day 
s 
kg 
   
365 400 , 86 
000 , 1 
3 m 
Source: Previous version of this model report (BSC 2001 [DIRS 155974]). 
NOTE: Colors are used only to discriminate among flux zones. UTM = Universal Transverse Mercator. 
Figure 6-42. Flux Zones Used for Comparing Death Valley Regional Flow System Flow Model and 
Site-Scale Flow Model Fluxes 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-147 November 2004 
Output DTN: LA0304TM831231.002. 
NOTE: Blue lines refer to head contours; red lines refer to particles. Arcs correspond to distances of 5-km, 20-km, 
and 30-km from the repository. The left panel plots all flow paths projected onto a north-south vertical plane; 
the right panel is the flow paths in plan view. The 0 in the left panel corresponds to the mean sea level. 
Figure 6-43. Flow Paths from the Repository and Hydraulic Head Contours Simulated with the SZ 
Site-Scale Flow Model 
6.7 EVALUATION OF ALTERNATIVE MODELS 
6.7.1 Large Hydraulic Gradient Alternative Conceptual Model 
An overview of the large hydraulic gradient (LHG) ACM is presented below, followed by 
discussions of the model setup used in evaluating the ACM and of the results of the evaluation. 
The section concludes with an assessment of the impact of the LHG ACM on the SZ site-scale 
flow model. The evaluation of ACMs associated with the LHG is taken from The Site-Scale SZ 
Flow Model for Yucca Mountain: Calibration of Different Conceptual Models and Their Impact 
on Flow Paths (Zyvoloski et al. 2003 [DIRS 163341]). 
6.7.1.1 Overview 
Alternative conceptualizations have been formulated, which remove the extensive set of features 
north of Yucca Mountain but divide the model domain along the Claim Canyon caldera into 
northern and southern zones, allowing different permeabilities to be assigned in the north versus 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-148 November 2004 
the south within the same hydrogeologic unit. By creating a distributed region of lower 
permeability in the northern portion of the model, the LHG can be simulated in the flow domain. 
Using this basic conceptualization, different models incorporating the northwest-southeast 
trending fault zone just north of Yucca Mountain, the Ghost Dance fault, and the Dune Wash 
fault have been formulated to evaluate the sensitivity of the base case model to different 
conceptualizations of the LHG. 
6.7.1.2 Setup 
The alternative conceptualizations of the LHG do not make use of the extensive feature set north 
of Yucca Mountain, and these have been removed from the base case model grid (Figure 6-6), 
thereby simplifying the grid in the alternative conceptualizations considered for the LHG. 
Instead, the hydrogeologic units have been divided into northern and southern zones at the Claim 
Canyon caldera boundary. Differing permeabilities can be assigned in each zone to each 
hydrologic unit. Two variants of this basic approach are considered: one uses only the alteration 
zone, whereas the other includes the alteration zone and a zone to represent the 
northwestsoutheast trending fault zone just north of Yucca Mountain (Feature 2 in Figure 6-6). 
These models are referred to as the altered, no fault (ANF) and altered, with fault (AWF) 
models, respectively. Although there are fewer discrete features in the altered models than in the 
base case model, there are actually a greater number of calibration parameters. This increase is a 
result of breaking the hydrogeologic units into independent northern and southern zones. A third 
alternative model, which adds features to the AWF model to account for the Ghost Dance fault 
and the Dune Wash fault, was formulated to improve the calibration obtained with the AWF 
conceptual models. This third alternative conceptual model is referred to as the AWF/GDF 
model. 
The alternative models resulted only in changes to the computation grid that was necessary to 
implement these alternative formulations of the hydrogeology. The alternative models were 
calibrated in a manner identical to that previously described for the SZ site-scale flow model. 
Waterlevel contour maps and particle tracks were generated based on the water levels predicted 
by the alternative models in a manner similar to that previously described for the SZ site-scale 
flow model. 
6.7.1.3 Results 
Water levels predicted by the SZ site-scale flow model and the LHG model at selected 
observation points are presented in Table 6-21. The calibrated permeability values, the SZ 
site-scale flow model, and the LHG model are presented in Table 6-22. All models adequately 
reproduced the gradient in the flow path downstream of the repository, and each model has 
similar sum-of-the-squared residuals on an overall basis. However, the simulations of the 
conceptual models that include the altered zone in the north matched better waterlevel 
observations in the low-gradient region than the simulation with the SZ site-scale flow model. In 
addition, all models capture the upward gradient from the carbonate aquifer. The close 
agreement of the calibrated permeabilities of the Bullfrog Tuff from each model also suggests 
that there are no significant differences in the specific discharge beneath the repository for the 
various conceptualizations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-149 November 2004 
The flow paths resulting from the simulations with the various conceptual models are shown in 
Figures 6-44 (ANF), 6-45 (AWF), and 6-46 (AWF/GDF). Although the flow paths predicted by 
the ANF and AWF conceptual models are similar to one another, they are noticeably different 
from the flow paths predicted by the simulations of the SZ site-scale flow model. The SZ 
site-scale flow model produces flow paths that trend in a southeasterly direction from the 
repository site (see Figure 6-43). Further analysis of the flow paths indicates that the fluid 
particles travel in the same units, predominantly the Bullfrog tuff and the alluvial units, 
regardless of the model, and do not reach the carbonate aquifer. This is because of the pervasive 
upward gradient and confining unit that separates the alluvial units and the carbonate aquifer. 
Because the transport times are directly proportional to the permeability values, a qualitative 
transport-time comparison with SZ site-scale flow model results per unit can be inferred from the 
calibrated permeabilities in Table 6-22. The Bullfrog tuff has a calibrated value about 30 percent 
higher in the AWF/GDF model than in the SZ site-scale flow model. This is within the 
uncertainty range for specific discharge discussed in Section 6.8.5.2. 
Table 6-21. SZ Site-Scale Flow Model Compared with Alternative Conceptual Models Selected 
Residuals from Models 
Residuals (Model - Measured), m 
Well ID 
Measured 
Head, (masl) 
SZ SS 
Flow 
Model 
ANF 
Model 
AWF 
Model 
AWF/GDF 
Model 
Characteristic 
of Head Measurement 
UE-25 WT #18 730.8 3.83 6.20 1.58 2.75 Low gradient 
UE-25 WT #4 730.8 3.63 0.23 0.41 2.65 Low gradient 
UE-25 WT #15 729.2 4.65 1.57 1.62 4.15 Low gradient 
USW G-4 730.6 4.38 0.65 0.78 3.36 Low gradient 
USW SD-6 731.2 3.61 -0.37 -0.28 2.24 Low gradient 
USW SD-7 727.6 6.50 3.05 3.16 5.68 Low gradient 
USW SD-9 731.1 3.51 -0.29 -0.17 2.41 Low gradient 
UE-25 J-11 732.2 -0.63 -0.63 -0.63 -0.57 Low gradient 
USW UZ-14 779.0 -44.10 -47.60 -48.20 -45.40 Moderate gradient 
USW G-1 754.2 -19.20 -23.00 -23.30 -18.60 Moderate gradient 
USW WT-7 775.8 -7.70 -17.50 -17.80 -7.80 Moderate gradient 
USW WT-10 776.0 5.50 -3.01 -2.91 -39.80 Moderate gradient 
USW H-5 upper 775.5 -40.90 -45.20 -45.30 -42.00 Moderate gradient 
USW H-6 lower 775.9 -12.00 -10.20 -10.30 13.50 Moderate gradient 
UE-25 WT #6 1034.6 -89.34 -211.76 -289.47 -297.20 Possibly perched 
USW G-2 1020.2 -86.41 -209.63 -283.92 -286.40 Possibly perched 
UE-25 p #1 (Lwr 
Intrvl) 
752.4 -12.73 -13.90 -14.89 -17.60 Upward gradient 
Output DTN: LA0304TM831231.002. 
Source: Zyvoloski et al. (2003 [DIRS 163341], Table 1). 
NOTE: *ANF = altered, no fault; AWF = altered, with fault; AWF/GDF = altered, with fault/Ghost Dance fault; 
masl = meters above sea level; SS = site-scale ; SZ = saturated zone 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-150 November 2004 
Table 6-22. Comparison of Selected Parameter Values for Alternate Conceptual Models 
Hydrogeologic Unit or Feature Permeability (m2) or Permeability Multiplication Factor (**) 
Base Case ANF* AWF* AWF/GDF* 
Lower Carbonate Aquifer 5.00  10-14 3.29  10-14 3.30  10-14 1.96  10-14 
Older Volcanic Confining Unit 2.00  10-16 1.03  10-16 1.00  10-16 5.70  10-16 
Older Volcanic Aquifer 5.00  10-16 1.00  10-15 1.00  10-15 1.52  10-14 
Lower Volcanic Confining Unit 2.00  10-15 1.28  10-16 1.54  10-16 1.79  10-13 
Crater Flat-Tram 2.36  10-13 2.23  10-13 1.73  10-13 3.38  10-14 
Crater Flat-Bullfrog 1.54  10-11 2.00  10-11 2.00  10-11 2.02  10-11 
Crater Flat-Prow Pass 8.00  10-12 1.01  10-13 1.00  10-13 7.19  10-14 
Upper Volcanic Confining Unit 5.00  10-14 1.52  10-15 1.87  10-15 1.55  10-14 
Upper Volcanic Aquifer 8.00  10-14 1.00  10-14 1.00  10-14 8.25  10-15 
Lava Flow Aquifer 1.00  10-12 4.85  10-12 4.89  10-12 7.81  10-12 
Limestone Aquifer 1.00  10-12 1.87  10-11 1.94  10-11 8.26  10-11 
Valley Fill Aquifer 5.00  10-12 5.00  10-14 5.01  10-14 4.93  10-14 
Lower Carbonate Aquifer (North) - 3.30  10-16 2.18  10-16 5.00  10-16 
Older Volcanic Confining Unit (North) - 9.59  10-16 1.27  10-15 5.64  10-19 
Older Volcanic Aquifer (North) - 3.28  10-16 3.32  10-16 2.20  10-16 
Lower Volcanic Confining Unit (North) - 1.00  10-16 1.00  10-16 1.08  10-15 
Crater Flat-Tram (North) - 1.00  10-16 1.00  10-16 2.14  10-15 
Crater Flat-Bullfrog (North) - 2.55  10-13 1.00  10-13 1.34  10-14 
Crater Flat-Prow Pass (North) - 6.12  10-15 5.00  10-15 2.83  10-14 
Upper Volcanic Confining Unit (North) - 8.04  10-16 8.00  10-16 9.83  10-16 
Upper Volcanic Aquifer (North) - 3.00 10-15 3.00  10-15 2.52  10-14 
Lava Flow Aquifer (North) - 2.96  10-12 2.99  10-12 1.06  10-11 
Limestone Aquifer (North) - 4.31  10-13 4.42  10-13 5.87  10-12 
Fortymile Wash Fault** 10 5.6 5.6 - 
Spotted Range-Mine Mountain Zone** 11.8 18.3 18.2 - 
Imbricate Fault Zone** 1 5 5 - 
Crater Flat Fault 5.00  10-14 3.19  10-14 3.47  10-14 4.57  10-13 
Crater Flat Fault (North) - 3.56  10-14 4.52  10-14 1.21  10-12 
U.S. Highway 95 Fault - 9.36  10-15 9.60  10-15 1.21  10-14 
Alluvial Uncertainty Zone 3.20  10-12 3.00  10-12 3.00  10-12 3.13  10-11 
Lower Fortymile Wash Zone 5.00  10-12 5.95  10-12 5.39  10-12 6.81  10-12 
Northwest Trending Fault Zone - - 3.87  10-13 1.55  10-11 
Source: Zyvoloski et al. (2003 [DIRS 163341], Table 2). Output DTN: LA0304TM831231.002. 
NOTE: *ANF altered, no fault. 
AWF altered, with fault. 
AWF/GDF altered, with fault/Ghost Dance fault. 
** Permeability Multiplication Factor is used to multiply the permeability in the grid macro that has the 
multiplier 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-151 November 2004 
Source: Zyvoloski et al. (2003 [DIRS 163341], Figure 6). 
NOTE: The red lines indicate flow paths. 
UTM = Universal Transverse Mercator. 
Figure 6-44. Predicted Flow Paths from the Water Table beneath the Repository for the Altered, No 
Fault Alternative Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-152 November 2004 
Source: Zyvoloski et al. (2003 [DIRS 163341], Figure 7). 
NOTE: The red lines indicate flow paths. 
UTM = Universal Transverse Mercator 
Figure 6-45. Predicted Flow Paths from the Water Table beneath the Repository for the Altered, with 
Fault Alternative Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-153 November 2004 
535000 540000 545000 550000 555000 560000 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
Source: Zyvoloski et al. (2003 [DIRS 163341], Figure 8). 
NOTE: The blue lines indicate flow paths. 
Figure 6-46. Predicted Flow Paths from the Water Table Beneath the Repository for the Altered with 
Fault/Ghost Dance Fault Alternative Model 
As described in Section 7.3, the flow paths predicted by the SZ site-scale flow model are 
consistent with the flow paths inferred from geochemical and isotopic data shown in 
Figures 6-47 and 7-6. The ANF and AWF alternative models produce flow paths of particles 
leaving the repository that are more southerly in direction than those of the SZ site-scale flow 
model and, arguably, significantly different from the interpreted flow paths from the 
geochemistry. The more southeasterly direction predicted by the SZ site-scale flow model is due 
to the east-west barrier feature that is not present in the ANF and AWF conceptual models. This 
feature acts as a dam to keep the head elevated in the north, but in the process, also blocks water 
flow from the north. 
UTM Easting (m) 
UTM Northing (m) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-154 November 2004 
Source: See Appendix A, Figure A6-62. 
NOTE: Base map shows borehole designators and inserts; for reference see Figure A6-5 and Table A4-3. 
UTM = Universal Transverse Mercator 
Figure 6-47. Groundwater Flow Paths in SZ Interpreted from Groundwater Chemistry and Isotope 
Compositions 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-155 November 2004 
Because the ANF and AWF models are forced to honor the available head data, the calibration 
process adjusts for this blockage by determining permeability distributions that allow water from 
Crater Flat (west of Yucca Mountain) to enter the repository area. Although the alternative 
conceptual models produced a level of calibration equal to or better than the original model, this 
adjustment results in the calibration of these alternative models not achieving as good a match as 
the SZ site-scale flow model in those few moderate gradient waterlevel wells (750 m to 780 m) 
just to the west of Yucca Mountain. 
To correct these deficiencies in the ANF and AWF alternative models, the AWF/GDF model 
was formulated. The AWF/GDF model augments the structures present in the AWF model with 
two permeability features, the Ghost Dance fault and the Dune Wash fault, and an additional four 
parameters associated with the moderate gradient region. The Ghost Dance fault runs parallel 
and to the east of the Solitario Canyon fault. The Dune Wash fault is a northwest-southeast 
trending fault splay of the Ghost Dance fault. Both features are shown in Figure 6-3. 
Calibration with the additional parameters noticeably improves the model in the moderate 
gradient region, with little deterioration of the overall fit. The more accurate match to the heads 
in the moderate gradient region results in particle flow paths (Figures 6-44 to 6-46) that more 
closely resemble those inferred from geochemistry. Therefore, the AWF/GDF model is 
considered a plausible alternative model to the SZ base-scale flow model and an improvement 
over the other two models, which assume only altered rock of lower permeability north of Yucca 
Mountain. The predicted flow paths and overall flux were similar between the base case and 
AWF/GDF models. 
6.7.1.4 Assessment 
The SZ site-scale flow model and three alternative conceptual models representing a variety of 
approaches for interpreting the cause of the LHG north of Yucca Mountain were investigated 
using calibration to waterlevel data, followed by a comparison of predicted flow paths from the 
repository. Although the calibrations may not be unique, several important data sets were 
matched by all of the conceptual models. The low hydraulic gradient in the area to the 
south-southeast of Yucca Mountain was modeled accurately in all models, with the alternative 
conceptual models producing better head matches. 
The largest potential differences observed between the SZ site-scale flow and alternative 
conceptual models are found in the flow paths predicted by the models. The analyses of the base 
case, ANF, and AWF models show that the flow path could be sensitive to the conceptual model 
of the LHG. To address the difficulties encountered by the ANF and Altered, with fault models 
in matching heads near the Solitario Canyon fault, the AWF/GDF model was evaluated. The 
AWF/GDF model contains additional parameters designed to capture the moderate gradient 
more accurately. With the additional parameterization, this model produced flow paths similar 
to the SZ site-scale flow model. 
The similarity of the SZ site-scale flow and AWF/GDF models suggests that the 
conceptualization of the LHG has little effect on the SZ site-scale flow model results. Apparent 
differences in flow paths in the ANF and AWF models are most likely due to not representing 
accurately the moderate gradient head observations and do not represent important differences in 
hydrologic conditions for the different conceptual models of the LHG. Thus, the SZ site-scale 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-156 November 2004 
flow model, in its role as a TSPA tool, is adequate. The uncertainty associated with the LHG 
models is discussed in Section 6.8.1. 
6.7.2 Solitario Canyon Fault Depth Alternative Conceptual Model 
An overview of the Solitario Canyon fault ACM is presented below followed by discussions of 
the model setup used in evaluating the ACM and of the results of the evaluation. The section 
concludes with an assessment of the impact of the Solitario Canyon fault ACM on the SZ 
site-scale flow model. 
6.7.2.1 Overview 
The Solitario Canyon fault and its east and west branches make up three of the 17 discrete 
geologic features and regions represented with distinct hydrological properties in the 
SZ site-scale flow model. The Solitario Canyon fault separates Crater Flat from Yucca 
Mountain and is shown in Figure 6-3. The Solitario Canyon fault consists of generally 
north-south trending features just to the west of Yucca Mountain. Both east and west branches 
consist of generally north-northeast trending linear features, also just to the west of Yucca 
Mountain. The representation of the Solitario Canyon fault is an important part of the SZ 
site-scale flow model because it can potentially control flow from Crater Flat to Fortymile Wash. 
The impact on the model of these features is to generate a higher hydraulic gradient to the west 
of Yucca Mountain and to impede flow from Crater Flat to Yucca Mountain. This effect on flow 
is important in determining the amount of alluvial material that groundwater flowing from 
beneath the repository region passes through en route to the accessible environment. 
6.7.2.2 Setup 
The SZ site-scale flow model includes the Solitario Canyon fault as a discrete feature that 
extends from the top of the water table to the bottom of the model. To investigate the 
importance of Solitario Canyon fault depth, an alternative conceptualization was simulated in 
which the fault extends from the water table only to the top of the carbonate aquifer. This 
alternative was identical to the SZ site-scale flow model in all other respects except for the 
Solitario Canyon fault properties. The alternative resulted only in changes to the computation 
grid that was necessary to implement this alternative formulation of the fault. The alternative 
model was calibrated in a manner identical to that previously described for the SZ site-scale flow 
model (see Section 6.6). Waterlevel contour maps and particle tracks were generated based on 
the water levels predicted by the alternative model in a manner similar to that previously 
described for the SZ site-scale flow model. 
6.7.2.3 Results 
The Solitario Canyon fault depth, is referred to as the shallow fault alternative model. This 
alternative is identical to the SZ site-scale flow model (Section 6.6) in all respects except for the 
Solitario Canyon fault properties. Table 6-23 compares the modeled head values from the 
shallow fault alternative model for the 32 wells in the low-gradient region to the south and east 
of Yucca Mountain with measured values and values from the base case model. Locations of the 
wells in Table 6-23 are shown in Figure 6-17. This area was chosen for comparison because of 
its influence on the specific discharge 5 km from the repository, which is an important 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-157 November 2004 
performance assessment measure. To provide a quantitative measure of the calibration of the 
shallow fault alternative model versus the SZ site-scale flow model, modeled heads at selected 
wells and waterlevel contours over the model domain can be compared. As seen from the 
comparison of modeled heads in Table 6-23, this simulation produced essentially the same result 
as the original SZ site-scale flow model with the deeper fault zone. For the shallow fault case, 
however, the calibrated permeability for the fault was approximately 25 percent lower than the 
permeability for the original deeper fault. 
Table 6-23. Observed and Computed Head Data Compared to Shallow Solitario Canyon Fault 
Alternative Conceptual Model 
Site 
Name 
Fig. 
6-40 
Label 
(UTM) 
(m) 
(UTM) 
(m) 
z 
(elevation) 
(m) 
Observed 
Head 
Data 
(m) 
SZ SS Flow 
Model 
Results (m) 
Shallow 
Fault Model 
Results (m) Weight 
UE-25 
WT #18 
7 549468 4080238 722.1 730.8 734.67 734.93 20 
UE-25 
WT #4 
10 550439 4079412 709 730.8 734.46 734.70 20 
UE-25 
WT #15 
11 554034 4078694 698.7 729.2 733.87 734.02 20 
USW G- 
4 
12 548933 4078602 542.2 730.6 734.5 734.77 20 
UE-25 
WT #14 
14 552630 4077330 703.6 729.7 733.79 733.95 20 
USW 
WT-2 
15 548595 4077028 702 730.6 734.18 734.46 20 
UE-25 c 
#1 
16 550955 4075933 473.2 730.2 733.92 734.11 20 
UE-25 c 
#3 
17 550930 4075902 474.3 730.2 733.92 734.11 20 
UE-25 c 
#2 
18 550955 4075871 553.2 730.2 733.9 734.10 20 
UE-25 
WT #13 
19 553730 4075827 703.8 729.1 733.35 733.47 20 
USW 
WT-1 
21 549152 4074967 708.4 730.4 733.86 734.05 20 
USW G- 
3 
22 547543 4074619 318.1 730.5 734.96 738.02 20 
UE-25 
J-13 
23 554017 4073517 354.8 728.4 732.74 732.83 20 
UE-25 
WT #17 
25 549905 4073307 705.4 729.7 733.58 733.70 20 
UE-25 
WT #3 
27 552090 4072550 705.8 729.6 733.08 733.18 20 
UE-25 
WT #12 
29 550168 4070659 702.6 729.5 732.92 732.89 20 
USW 
WT-11 
30 547542 4070428 691.9 730.7 733.71 733.43 20 
UE-25 
J-12 
31 554444 4068774 659.6 727.9 731.44 731.48 20 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-158 November 2004 
Table 6-23. Observed and Computed Head Data Compared to Shallow Solitario Canyon Fault 
Alternative Conceptual Model (Continued) 
Site 
Name 
Fig. 
6-40 
Label 
x 
(UTM) 
(m) 
y 
(UTM) 
(m) 
z 
(elevation) 
(m) 
Observed 
Head 
Data 
(m) 
SZ SS Flow 
Model 
Results (m) 
Shallow 
Fault Model 
Results (m) Weight 
UE-25 
JF-3 
32 554498 4067974 662.7 727.8 731.15 731.19 20 
Cind-RLite 
Well 
33 544027 4059809 710.2 729.8 737.49 735.75 20 
USW H- 
1 tube 3 
81 548727 4079926 562.5 730.6 734.63 734.89 20 
USW H- 
1 tube 4 
82 548727 4079926 680.5 730.8 734.65 734.92 20 
UE-25 b 
#1 lower 
85 549949 4078423 8.8 729.7 735.53 735.84 20 
UE-25 b 
#1 
upper 
86 549949 4078423 366.2 730.6 734.34 734.58 20 
USW H- 
4 upper 
89 549188 4077309 395.5 730.4 734.25 734.51 20 
USW H- 
4 lower 
90 549188 4077309 45 730.5 735.1 735.48 20 
USW H- 
3 upper 
91 547562 4075759 576.9 731.5 734.48 736.23 20 
USW 
SD-6 
94 547578 4077550 725.9 731.2 734.84 735.21 20 
USW 
SD-7 
95 548384 4076499 637.7 727.6 734.13 734.43 20 
USW 
SD-9 
96 548550 4079256 678.3 731.1 734.64 734.91 20 
USW 
SD-12 
97 548492 4077415 696.7 730.0 734.31 734.61 20 
UE-25 
J-11 
107 563799 4071058 687.2 732.2 731.57 731.57 20 
Output DTN: LA0304TM831231.002. 
SS = site-scale; SZ = saturated zone; UTM = Universal Transverse Mercator. 
Groundwater flow paths in the base case SZ site-scale flow model and in the alternative 
shallower Solitario Canyon fault model were evaluated using particle tracking. Particle paths 
from beneath the repository show similarity between those in the alternative model to those in 
the SZ site-scale flow model; however, the flow paths in the cross section indicate that the paths 
crossing the southern branches of the Solitario Canyon fault do not extend to depths as great as 
in the SZ site-scale flow model (Figures 6-48 to 6-51). 
6.7.2.4 Assessment 
An analysis of flow paths in the SZ beneath Yucca Mountain was completed using an alternative 
representation of the Solitario Canyon fault. The results of the analysis were compared to 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-159 November 2004 
SZ site-scale flow model representation of the Solitario Canyon fault. The comparison resulted 
in the following. 
 Bothconceptualizations of the Solitario Canyon fault yield the same flow paths from the 
water table underneath the repository to the accessible environment. 
 Particles started to the west of the Solitario Canyon fault do not extend to a depth as 
great as in the SZ site-scale flow model (see Figures 6-49 and 6-51). 
 For the shallow-fault ACM, the calibrated permeability for the fault was approximately 
25 percent lower than for the fault in the SZ site-scale flow model. Thus, transport times 
for the ACM will not be shorter than for the SZ site-scale flow model. 
 Based on this SZ subsystem analysis, which yielded similar flow path for both 
conceptualizations of the Solitario Canyon fault, it is concluded that the alternative 
representation of the Solitario Canyon fault will not change the SZ barrier performance, 
and therefore does not need to be propagated into TSPA. 
6.8 UNCERTAINTY 
Characterizing and understanding the flow through the SZ is important for assessing the overall 
containment strategy for safely storing radioactive materials at the Yucca Mountain repository. 
Uncertainty in flow modeling arises from a number of sources including, but not limited to, the 
conceptual model of the processes affecting groundwater flow, waterlevel measurements and 
simplifications of the model geometry, boundary conditions, hydrogeologic unit extent and 
depth, and the values of permeability assigned to hydrogeologic units. This section discusses 
and attempts to quantify uncertainties in the SZ site-scale flow model. In addition to the 
discussion in this section, parameter uncertainty is addressed in the model abstraction document 
(BSC 2004 [DIRS 170042]). This document includes additional quantitative analysis on 
horizontal anisotropy in permeability and groundwater specific discharge. Saturated Zone 
In-Situ Testing (BSC 2004 [DIRS 170010]) addresses the uncertainty related to the spatial 
distribution of the observation wells. 
6.8.1 Large Hydraulic Gradient 
An area of a LHG north of the high-level radioactive waste repository at Yucca Mountain has 
been inferred from previous hydraulic head measurements. To simulate this feature in the 
Yucca Mountain SZ site-scale flow model reported in the previous revision to this model report, 
a low-permeability east-west feature was incorporated into the model domain north of Yucca 
Mountain. The presence of this feature has yet to be confirmed by field investigations. Data that 
are more recent appear to indicate that the gradient in this area may be significantly lower than 
originally thought (BSC 2004 [DIRS 170009]), although high gradients still appear to be present 
in which a low-permeability east-west feature is incorporated into the model domain north of 
Yucca Mountain. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-160 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
-2000 
-1000
0 
1000 
Elevation (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
Output DTN: LA0304TM831231.002. 
NOTE: Repository outline (shown with the bold red line) and nodes along the Solitario Canyon fault (shown with 
orange crosses). The left panel plots cross section of all flow paths projected onto a north-south vertical 
plane; the right panel is the flow paths in plan view. The 0 in the left panel corresponds to the mean sea 
level. Blue lines indicate simulated groundwater flow paths from beneath the repository. 
UTM = Universal Transverse Mercator 
Figure 6-48. Simulated Groundwater Flow Paths from Beneath the Repository for the SZ Site-Scale Flow 
Model Deep Solitario Canyon Fault 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-161 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
-2000 
-1000
0 
1000 
Elevation (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
Output DTN: LA0304TM831231.002 
NOTE: Repository outline (shown with the bold red line) and nodes along the Solitario Canyon fault (shown with 
orange crosses). The left panel plots cross section of all flow paths projected onto a north-south vertical 
plane; the right panel is the flow paths in plan view. The 0 in the left panel corresponds to the mean sea 
level. Blue lines indicate simulated groundwater flow paths from the west side of the Solitario Canyon Fault. 
UTM = Universal Transverse Mercator 
Figure 6-49. Simulated Groundwater Flow Paths from the West Side of Solitario Canyon Fault (Blue 
Lines) for the SZ Site-Scale Flow Model Deep Solitario Canyon Fault 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-162 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
-2000 
-1000
0 
1000 
Elevation (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
Output DTN: LA0304TM831231.002. 
NOTE: Repository outline (shown with the bold red line) and nodes along the Solitario Canyon fault (shown with 
orange crosses). The left panel plots cross section of all flow paths projected onto a north-south vertical 
plane; the right panel is the flow paths in plan view. The 0 in the left panel corresponds to the mean sea 
level. Blue lines indicate simulated groundwater flow paths from beneath the repository. 
UTM = Universal Transverse Mercator 
Figure 6-50. Simulated Groundwater Flow Paths from Beneath the Repository for the Alternative Case 
(Shallow Solitario Canyon Fault) SZ Site-Scale Flow Model 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-163 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
-2000 
-1000
0 
1000 
Elevation (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
Output DTN: LA0304TM831231.002. 
NOTE: Repository outline (shown with the bold red line) and nodes along the Solitario Canyon fault (shown with 
orange crosses). The left panel plots cross section of all flow paths projected onto a north-south vertical 
plane; the right panel is the flow paths in plan view. The 0 in the left panel corresponds to the mean sea 
level. Blue lines indicate simulated groundwater flow paths from the west side of Solitario Canyon Fault. 
UTM = Universal Transverse Mercator 
Figure 6-51. Simulated Groundwater Flow Paths from the West Side of Solitario Canyon Fault for the 
Alternative Conceptual Model of the Shallow Solitario Canyon Fault 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-164 November 2004 
The sensitivity of the estimated groundwater flow paths and specific discharge to each of the 
conceptual models of the LHG has been investigated by both recalibrating the numerical model 
to fit conditions appropriate to each conceptual model and noting the resulting changes in the 
groundwater flow regime. The SZ site-scale flow model uses the uniform permeability of the 
hydrogeologic units plus permeabilities (or permeability multipliers) associated with features as 
calibration parameters. As discussed above, the SZ site-scale flow model calibration included 
low permeability zones and an east-west barrier north of Yucca Mountain to simulate the high 
gradient area (Figure 6-5). The alternative conceptualizations of the LHG do not make use of the 
extensive feature set north of Yucca Mountain, and these have been removed in the alternative 
models (Figure 6-6). To incorporate the area of extensive hydrothermal alteration in the Claim 
Canyon Caldera north of Yucca Mountain, the hydrogeologic units have been divided into 
distinct northern and southern zones. The AWF and AWF/GDF models differ from each other 
only by the inclusion of a zone that represents the northwest-southeast trending fault zone just 
north of Yucca Mountain (Feature 2 in Figure 6-6). 
Although the number of features used in the alternative models is less than in the original SZ 
site-scale flow model, the number of calibration parameters has been increased. This increase is 
a consequence of dividing the hydrogeologic units into northern and southern zones. The list of 
calibrated versus measured observations for selected observation points (calibration targets) is 
given in Table 6-18. In general, the simulations of the alternative conceptual models better 
match observations in the low gradient region than the simulation within the original SZ 
site-scale flow model. The inclusion of the additional northwest-southeast trending fault zone in 
the second of the alternative conceptual models does not seem to improve the calibration. 
The flow paths resulting from the simulation of the alternative conceptual models and original 
model are shown in Figures 6-44 to 6-46. Although the flow paths predicted by the simulation of 
the alternative conceptual models are similar, they are noticeably different from the flow paths 
predicted by the simulations of the original SZ site-scale conceptual model. The original model 
produces flow paths that trend in a southeasterly direction from the repository site (Figure 6-44). 
This result is consistent with the path lines inferred from geochemical shown in Figure 6-47. 
The AWF and AWF/GDF models produce path lines of particles leaving the repository that are 
more southerly in direction than those of the original model (Figures 6-45 and 6-46). An indepth 
analysis of the path lines indicates that the fluid particles travel in the same units-basically 
the Bullfrog tuff and the alluvial unitsregardless of the model, and do not reach the carbonate 
aquifer. The net result of the flow paths from the alternative conceptualization is a relatively 
shorter traverse through the alluvial units compared to the paths for the original model. It should 
be noted that the more southeasterly component of the original model is due to the east-west 
barrier feature that is not present in the alternative models. This feature not only acts as a dam to 
keep the head elevated in the north but also blocks water from the north, thus allowing water 
from Crater Flat to enter the repository area. The alternative models lack this feature and allow 
the water to flow directly south. Because the flow paths and overall flux were smaller between 
the AWF/GDF and the SZ site-scale flow model, the uncertainty in the LHG is captured in the 
range of uncertainty associated with the horizontal anisotropy (Section 6.8.3) and included in the 
SZ flow and transport abstraction model (BSC 2004 [DIRS 170042]). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-165 November 2004 
6.8.2 Perched Water on Flow Paths and Specific Discharge 
Perched water was not explicitly modeled in the SZ site-scale flow model, although it is noted 
here that all three conceptualizations of the LHG produced water levels in wells UE-25 WT#6 
and UE-25 G-2 (suspected to be perched) that were much lower than the reported water levels. 
From Table 6-21, it can be seen that the original model is about 80 m to 90 m low, indicating a 
water level of about 930 m in this area to the north of Yucca Mountain; this is consistent with the 
latest waterlevel interpretation in that area (BSC 2004 [DIRS 170009]. The alternative models 
of the LHG yield water levels in the UE-25 WT#6, UE-25 G-2 area that are 130 m lower than the 
SZ site-scale conceptual model, indicating a much more abrupt change in head. This area has the 
steepest hydraulic gradient in the model; thus, it is not surprising that such differences in the 
models occur. As these hydraulic gradients occur over only several elements, addition 
discretization may be needed to quantify possible effects on flow direction and specific 
discharge. Fortunately, the LHG is upgradient of the repository and only minimally affect 
particle flow paths and transport times (see Figure 6-46). Therefore; uncertainty due to perched 
water on flow paths and specific discharge is not propagated forward into the SZ flow and 
transport abstraction model (BSC 2004 [DIRS 170042]). 
6.8.3 Anisotropy 
Both vertical and horizontal anisotropy can affect the flow path, flow direction, and specific 
discharge. 
6.8.3.1 Vertical Anisotropy 
The SZ site-scale flow model was calibrated using 114 head measurements from wells within the 
model domain as described in Section 6.6. Removing background vertical anisotropy from the 
model had the following effects on computed heads for these wells and lateral boundary fluxes. 
The difference between heads computed for the target wells with and without background 
vertical anisotropy was less than the difference between heads computed using the model and 
measured heads except for seven of the 114 measurements. 
 Well UE-29a-2 Hydraulic Test Hole is located in the high-gradient region north of 
Yucca Mountain. Removing background vertical anisotropy resulted in a computed 
head 23 m lower than the model with vertical anisotropy. 
 Wells USW WT-10 and USW VH-1 are located west of Yucca Mountain. Removing 
background vertical anisotropy resulted in computed heads 12 m and 13 m lower than 
the model with vertical anisotropy. 
 Wells James H. Shaw, Richard Washburn (1), NC-Washburn-1X, and Richard 
Washburn (3) are located in the Amargosa Desert. Removing background vertical 
anisotropy resulted in computed heads approximately 1 m higher than the model with 
vertical anisotropy. 
Differences in fluxes through the boundary flux zones defined in Figure 6-42 exceeded 
30 percent for only two of the zones, W1 and W4, both of which are located on the western 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-166 November 2004 
boundary of the SZ site-scale flow model boundary. Overall, 10:1 vertical anisotropy yielded 
better flow calibration and was therefore kept unchanged in the SZ site-scale flow model 
6.8.3.2 Horizontal Anisotropy 
Incorporating anisotropy in the area of the north-south trending faults at Yucca Mountain into the 
SZ site-scale flow model discussed in Section 6.6 resulted in predicted hydraulic heads that were 
slightly closer to the observed heads than for the model calibration without anisotropy. The 
differences in predicted heads and their impacts on the specific discharge, the flow path 
direction, and flow path lengths in volcanic tuffs and alluvium were within the uncertainty 
ranges used in the TSPA (BSC 2004 [DIRS 170042]). More detailed analyses (including pathline 
analyses) were conducted to study the impact of horizontal anisotropy on specific discharge 
and flow path direction and length, (BSC 2004 [DIRS 170042], Section 6.5.1.2). These analyses 
use the anisotropy distribution specified in Saturated Zone In-Situ Testing (BSC 2004 
[DIRS 170010], Section 6.2.6). 
6.8.4 Representing Faults with Enhanced Permeability Grid Blocks 
Computational limitations (i.e., insufficient memory and/or processor speed) preclude the 
implementation of a finite-element model of the SZ model domain that explicitly models 
individual fractures and faults on a one-to-one scale. For example, if the exact location, 
orientation, and dimensions were known for each fracture/fault in the system, the number of 
elements (and computation time) required to model the system would increase by several orders 
of magnitude. Therefore, major faults are conceptualized in the SZ site-scale flow model as 
zones of enhanced permeability that simulate preferential flow in faults with grid blocks that are 
nominally 500  500 m in the horizontal directions. The situation is somewhat different in the 
vertical direction. Here, element depth is typically on the order of tens of meters at the fault 
termination depth (often the top of the regional carbonate aquifer). Thus, the depth of a fault 
zone is as accurate as the available geologic information. Nevertheless, fault properties are 
necessarily volume-averaged throughout an element. On the one hand, representing faults with 
500  500 m elements certainly accounts for the uncertainties in their geographic location. The 
discussion of the observed relationship between the pumping test and faults is provided in 
BSC (2004 [DIRS 170010]). On the other hand, the hydrogeologic properties are smeared 
across a relatively large area, precluding the use of some fault-specific site data in the calibration 
targets. Finally, it should be noted that Bower et al. (2000 [DIRS 149161]) studied 10 different 
grids generated from the same HFM (similar to that used in the SZ site-scale flow model) and 
found that model calibrations were sufficient with 500-m horizontal elements, and that further 
refinement produced little change in fluxes. 
Volume-averaged representations of faults are commonly used in numerical modeling. For 
example, studies of different conceptual models of the LHG have shown that its (modeled) 
representation had little impact on resulting flow paths as long as the system potentiometric 
surface was matched. Furthermore, because element permeability values are calibrated to field 
observations that are several grid blocks away from faults, it is believed that the large grid block 
representation is adequate for the purpose of flow modeling away from the fault. While the 
precise flow regime within the fault may not be representative, overall flow through the system, 
particularly at the model boundaries, is not significantly affected by the volume-averaged 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-167 November 2004 
approach. These studies give confidence that the representation of faults is adequate in the SZ 
site-scale flow model. 
6.8.5 Quantification of Groundwater Specific Discharge 
The specific discharge downgradient from the repository at Yucca Mountain, along with 
effective transport porosity, determines the rate at which groundwater and radionuclides move 
away from Yucca Mountain. The specific discharge, in turn, is a function of both the 
permeability of the rocks and alluvium and of the hydraulic gradient in this area. The hydraulic 
gradient, as discussed above, is sufficiently characterized to provide well-constrained input to the 
transport calculations. The purpose of this section is to discuss the permeability data for the 
volcanic rocks at Yucca Mountain and elsewhere at the NTS and the application of these data to 
calculations of specific discharge. 
As discussed in Section 6.4, several conceptual models have been evaluated with the common 
goal of reducing the uncertainty in specific discharge near the repository and downgradient in the 
alluvial aquifer. These efforts include: 
 Studying different conceptualizations of the Solitario Canyon fault 
 Studying different conceptualizations of the LHG 
 Mapping the vertical gradient 
 Investigating anisotropy effects 
 Investigating repository temperature effects. 
Investigating different conceptualizations of the Solitario Canyon fault is important because this 
fault regulates flow from Crater Flat (west of the fault) to Fortymile Wash (east of the fault). 
Conceptualizations include a shallower representation of the fault that terminates at the top of the 
carbonate aquifer (it originally went to the bottom of the SZ site-scale flow model, well into the 
carbonate aquifer). In the shallow fault model, neither the calibrated permeability of the fault 
nor the resulting path lines for fluid leaving the repository area change significantly. In both 
models, the flow remains primarily in the volcanic units due to an upward gradient in the 
carbonate aquifer. Furthermore, varying the ratio of vertical to horizontal permeabilities also has 
little effect. The important fault property is the east-west (across the fault) permeability. 
Different conceptualizations of the LHG are important because all previous models of the SZ 
near Yucca Mountain required a low permeability feature north of Yucca Mountain to explain 
the abrupt drop in heads in this area (from 1,200 m to 730 m). As discussed in Section 6.4.1, an 
excellent potentiometric surface calibration was obtained by modeling the large head change 
with geochemical alteration and ring faulting as a consequence of the formation on the Claim 
Canyon caldera north of Yucca Mountain. In all models of the LHG, fluid path lines and 
specific discharge are similar, primarily because this feature is upgradient of any flow that might 
originate from the repository at Yucca Mountain. The important conclusion to draw is that if the 
waterlevel calibration is accurate, the conceptualization of the LHG has little effect on specific 
discharge or flow path. 
The mapping of the vertical gradient at the contact between the volcanic and/or alluvial aquifer 
and the Carbonate Aquifer shows that the vertical gradient is upward along the fluid path lines 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-168 November 2004 
originating from the repository area. It can be inferred that for all reasonable climate scenarios, 
the flow paths will lie in the most permeable volcanic unit (likely the Bullfrog tuff), until they 
reach (and remain in) the alluvial aquifer. Therefore, it is important to carry forward a 
conceptualization of the vertical gradient in the SZ site-scale flow model. 
The SZ site-scale flow model included a vertical anisotropy ratio of 10:1 in many of the units as 
described in Section 6.4.3. Included faults were generally modeled as anisotropic features highly 
conductive along the fault (strike), and vertically of low conductivity in the direction across the 
fault (Figure 6-1). Results indicated that the effect of individual fault anisotropy is relatively 
unimportant. When a fault zone is calibrated to its minimum directional permeability (across the 
fault), even significant changes in the other directional permeabilities (vertical and strike) 
contribute little variation in the model results. For example, the Solitario Canyon fault zone is 
calibrated to its across-the-fault permeability. Increasing the vertical permeability by factors of 
10 and 1,000 times the across-the-fault value has little effect on model calibrations. 
There is an area of special concern in the SZ site-scale flow model with predominately 
north-south trending faults in the vicinity of Yucca Mountain. This zone is bounded by a 
quadrilateral with points (548712, 4065570), (554390, 4067050), (553647, 4080900), (547317, 
4081090) in UTM coordinates (~88 km2) and has a north-south to east-west anisotropy ratio in 
permeability. A detailed analysis of the anisotropy distribution applied to this zone can be found 
in Saturated Zone In-Situ Testing (BSC 2004 [DIRS 170010], Section 6.2.6). In the SZ 
site-scale flow model the effect of horizontal anisotropy in this area was incorporated with a 5:1 
anisotropy ratio. Calibration results were slightly closer to targets with this implementation of 
anisotropy. Although particle tracking was not performed, it is likely that the fluid path lines 
leaving the repository will have a more north-south trajectory than the original isotropic model. 
Particle path-line changes subject to the latest distribution of horizontal anisotropy in this zone 
will be studied in more detail in this model report. 
Incorporating increases in saturated-zone water temperature changes the specific discharge in a 
predictable manner. Creating a zone of elevated temperature near the repository simply 
decreases the transport time (and, thus, the specific discharge) in proportion to the decrease in 
the fluid viscosity due to temperature change. Increasing the average temperature from 30C to 
80C along a 5-km path decreases both the viscosity and transport time by a factor of two. The 
temperature impacts on groundwater flow are within the range of uncertainty in specific 
discharge considered in the SZ flow and transport simulations for TSPA (Section 6.5) 
6.8.5.1 Discussion of the Effect of Hydrogeologic Contact Uncertainty on Specific 
Discharge 
The HFM conceptual model for the SZ site-scale flow model was created from a variety of field 
data and exists in electronic form as Stratamodel surfaces (BSC 2004 [DIRS 170008]). There is 
uncertainty in the spatial positions of these surfaces primarily due to lack of data. These surfaces 
were used to generate the finite-element mesh such that each element is assigned those 
hydrogeologic properties found at the center of the element. There is interest in how 
uncertainties in the representation of hydrogeologic-unit horizontal locations affect flux or 
specific discharge calculations. Due to the coarseness of the finite-element mesh, some 
horizontal uncertainty in the HFM can be entertained. As long as the horizontal spatial 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-169 November 2004 
ambiguity in the location of hydrogeologic contacts is less than 250 m (one-half the grid block 
dimension), there is essentially no impact on model specific discharge or flux calculations. 
Because flow leaving the repository area is confined to a few of the most permeable units, the 
vertical dimension deserves special consideration. From the SZ site-scale flow model, it is 
known that the fluid leaves the repository area through the Bullfrog tuff and migrates to alluvial 
units. The flow paths in areal and vertical views are reproduced in Figure 6- 43. Note that the 
vertical thickness of the flowing zone varies between 100 and 400 m, and the elevation changes 
from 300 to 700 m above sea level. From Table 6-15, the spacing in this part of the finite 
element mesh varies from 10 to 50 m. Consider, for example, that the uncertainty in the vertical 
contact location of the Bullfrog tuff is 50 m in the portion of the model where the flow path is 
300 to 400 m thick. Changing a single elements hydrogeologic designation, either to or from 
Bullfrog tuff would result in a change to the local specific discharge by no more than a factor of 
50/300 (17 percent). This is well within the overall specific discharge uncertainty range. 
Unfortunately, the thin flow path between UTM Northing coordinates 4,070,000 and 
4,060,000 m (Figure 6-43) can be problematic. Here the fluid flow is vertically constrained to 
100 m. If the bottom contact of the Bullfrog tuff were to change by 50 m, this could result in a 
change to the specific discharge flux in that area of up to 50 percent. Fortunately, integrated 
specific discharge calculations will be affected to a lesser degree. The impacts of hydrogeologic 
contact location uncertainty are summarized below. 
 Sensitivity to uncertainty in the hydrogeologic contact surfaces in the horizontal 
directions is much less than in the vertical direction due to the averaging effect of 500-m 
grid block spacing. 
 The change in specific discharge due to the 50-m uncertainty in the vertical 
hydrogeologic surface can produce up to a 17 percent change in the local specific 
discharge near the repository and in the alluvial flow regions. 
 50-m uncertainty in the vertical hydrogeologic surface can produce up to a 50 percent 
change in the local specific discharge in the transitional zone (UTM Northing 
coordinates 4,070,000 to 4,060,000 m). 
Because of the averaging effect across elements in the integrated specific-discharge calculations 
(0 to 5 km, 0 to 20 km), a 50 percent regional change in a relatively small portion of the 0- to 
20-km compliance boundary affects model results only moderately. The range of uncertainty 
considered for specific discharge in the SZ flow and transport abstractions model is significantly 
greater than the uncertainty in the HFM (BSC 2004 [DIRS 170042], Section 6.5.2.1). 
6.8.5.2 Specific Discharge Uncertainty Range 
In previous transport models of the SZ, the specific discharge has varied from one-tenth of its 
nominal value to ten times its nominal value in performance assessment calculations (BSC 2001 
[DIRS 157132], Section 6.2.5). Based on recent calibration experience and the evaluation of 
permeability data from Yucca Mountain and other sites presented above, the range for the 
majority of the uncertainty in specified discharge may be limited to one-third of its nominal 
value to three times the nominal value. The nominal value was obtained from the calibration of 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-170 November 2004 
the SZ site-scale flow model (Section 6.6). Because of the linearity of the numerical model, the 
calibration of the model can be preserved by scaling the fluxes, recharge, and permeabilities in 
exactly the same manner. In the discussion below, we focus on the Bullfrog tuff unit because 
calibration experience has shown that, for all reasonable scenarios, the fluid particles leaving the 
repository area travel predominantly in this unit until the transition to the alluvial aquifer. 
From the reevaluation of the permeability data described above and the statistical summary of 
the permeability data given in Table 6-24, three important facts emerge. The first is that the 
upper 95 percent confidence interval for the mean permeability of the Bullfrog tuff from the 
cross-hole tests (3.4 x 1011 m2) is approximately three times the mean value (1.4 x 1011 m2). 
The mean value, in turn, is very close to the nominal calibration value of 1.5 x 1011 m2 obtained 
for the SZ site-scale flow model. Second, alternative conceptual models developed since the SZ 
site-scale flow model was calirated have resulted in a range of estimates for the permeability of 
the Bullfrog tuff that vary less than 100 percent from the nominal permeability value. Third, the 
permeability data from Yucca Mountain had a practical maximum of 8.0  1011 m2 for 
individual tests in highly fractured intervals in volcanic rock. Although this value exceeds the 
nominal value by a factor of five, uncertainty in the geometric-mean permeability is a more 
relevant measure of the uncertainty that should be considered in the numerical model because all 
units in that model are considered to be homogeneous and should have site-averaged rather than 
local permeabilities. Large values were measured in cross-hole tests in the C-wells complex near 
the Midway Valley fault, and, as discussed above, proximity to the fault was probably 
responsible for these permeability measurements. Based on this evidence, upper limits for 
permeabilities of the Bullfrog tuff (and, by inference, other units that are three times the nominal 
values) are realistic and appropriate. By similar reasoning, because the lower 95 percent 
confidence interval of the geometric-mean permeability of the Bullfrog tuff is approximately S 
of the mean value, this ratio is recommended for the lower limit in performance assessment 
calculations. 
In the 18-km compliance region (Figure 6-43), performance assessment calculations are also 
strongly influenced by travel of fluid in the alluvial aquifer. Recently, estimates of groundwater 
specific discharge in the SZ have been obtained from field-testing at the ATC (BSC 2004 
[DIRS 170010], Section 6.5.5). The ATC is approximately located at the boundary of the 
accessible environment, as specified in regulations for the Yucca Mountain Project, 
10 CFR 63.302 (10 CFR Part 63 [DIRS 156605]). The location of the ATC is approximately 
18 km from Yucca Mountain, and testing was performed in the alluvium aquifer. Estimates of 
groundwater specific discharge at the ATC range from 1.2 m/yr to 9.4 m/yr 
(DTN: LA0303PR831231.002 [DIRS 163561]). The simulated average specific discharge in 
this region of the SZ system, using the SZ transport abstraction model, ranges from 1.9 m/yr to 
3.2 m/yr for differing values of horizontal anisotropy in permeability. Correspondingly, the 
simulated average specific discharge in the volcanic aquifer near Yucca Mountain using the SZ 
transport abstraction model ranges from 0.31 m/yr to 0.87 m/yr for differing values of horizontal 
anisotropy in permeability. These results show that the average groundwater specific discharge 
tends to increase along the flow path from beneath Yucca Mountain to the south. This increase 
in the specific discharge is due to convergent groundwater flow in this region of the SZ system. 
These results also indicate that there is general consistency between the simulated specific 
discharge and the median values of uncertainty ranges estimated for the volcanic aquifer and the 
alluvial aquifer along the flow path. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-171 November 2004 
Table 6-36. Statistical Summary of Permeabilities Calculated from Single-Hole and Cross-Hole Tests at Yucca Mountain 
Single-Hole Tests 
Unit 
Topopah 
Spring Tuff 
Calico Hills 
Formation 
Prow Pass 
Tuff 
Bullfrog 
Tuff Tram Tuff 
Lava 
Flows 
Lithic 
Ridge Tuff 
Pre-Lithic 
Ridge Tuff 
(Older 
Tuff) 
Middle 
Volcanic 
Aquifer Mixed Tuffs 
Carbonate 
Aquifer 
Number of Tests 1 9 14 19 34 0 15 5 10 30 24 
Mean 7.84  1013 9.38  1014 2.85  1013 3.07  1014 1.00  1014  1.09  1014 4.52  1016 5.59  1014 1.34  1015 7.17  1014 
Lower 95% 
Confidence Interval 
for Mean 
 4.45  1014 8.13  1014 9.98  1015 4.03  1015  2.57  1015 1.87  1018 6.19  1015 4.56  1016 4.69  1014 
Upper 95% 
Confidence Interval 
for Mean 
 1.97  1013 9.95  1013 9.45  1014 2.49  1014  4.60  1014 1.09  1013 5.05  1013 3.95  1015 1.10  1013 
Minimum  2.72  1014 7.77  1015 2.28  1016 2.35  1016  8.35  1017 1.84  1018 1.85  1016 1.72  1018 1.69  1014 
Maximum  4.19  1013 1.40  1011 1.67  1012 1.18  1012  1.22  1012 4.49  1014 1.40  1012 3.53  1013 1.40  1012 
Cross-Hole Tests 
Calico 
Hills 
Formation 
Prow Pass 
Tuff 
Bullfrog 
Tuff Tram Tuff 
Middle 
Volcanic 
Aquifer 
Number of Tests 6 8 13 1 6 
Mean 1.68  1013 2.77  1012 1.37  1011 5.39  1011 1.78  1011 
Lower 95% 
Confidence Interval 
for Mean 
1.25  1013 1.78  1012 5.61  1012  8.33  1012 
Upper 95% 
Confidence Interval 
for Mean 
2.26  1013 4.31  1012 3.36  1011  3.81  1011 
Minimum 1.08  1013 1.44  1012 1.08  1012  7.19  1012 
Maximum 2.52  1013 7.19  1012 7.55  1011  5.75  1011 
Source: DTN: SNT05082597001.003 [DIRS 129714]. 
NOTE: Permeability values are given in units of meters-squared (m2). The Topopah Spring tuff corresponds to the upper volcanic aquifer (unit 16); the Calico Hills 
Formation corresponds to the upper volcanic confining unit (unit 15); and portions of the lithic ridge and pre-lithic ridge tuffs correspond to the lower volcanic 
confining unit (unit 11), the older volcanic aquifer (unit 10), and the older volcanic confining unit (unit 9). The middle volcanic aquifer includes the Prow Pass, 
Bullfrog, and Tram tuffs and associated bedded units (Luckey et al. 1996 [DIRS 100465], Figure 7). Other units correspond to hydrogeologic units of the 
same name. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-172 November 2004 
The additional data from the ATC both constitute new information on the specific discharge in 
the SZ and significantly reduce uncertainty in the specific discharge relative to the assessment by 
the expert elicitation panel. The range of estimated specific discharge at the ATC spans about a 
factor of 7.8 (i.e., 1.2 m/yr to 9.4 m/yr). This indicates a range of uncertainty in specific 
discharge that is somewhat less than one order of magnitude, which is considerably less than the 
degree of uncertainty of a factor 10 from the SZ Expert Elicitation Project (CRWMS M&O 1998 
[DIRS 100353], p. 3-43). Consequently, the uncertainty distribution for the groundwater specific 
discharge is reevaluated to reflect the reduced uncertainty. From this information, an uncertainty 
distribution in specific discharge is constructed, in which 80 percent of the probability is between 
one-third and three times the nominal value of specific discharge and the remaining 20 percent 
probability extending the range to 1/30 and 10 times the best estimate of the specific discharge. 
Note that the details, including figures, of the specific discharge distribution and associated 
sampling techniques are contained in Saturated Zone Flow and Transport Model Abstraction 
(BSC 2004 [DIRS 170042], Section 6.5.2.1). 
6.8.5.3 Remaining Uncertainties in Specific Discharge Estimates 
The analyses and corresponding assignment of an uncertainty range for the groundwater specific 
discharge assumes that the porous continuum approach is appropriate for the fractured volcanic 
tuffs. A remaining uncertainty is whether or not the continuum approach can be employed at the 
scale of the model. An alternative conceptual model not yet explicitly examined is one in which 
most of the flow from Yucca Mountain moves through faults rather than through the unfaulted 
rock. To test this alternative model, the known faults need to be included explicitly in the 
numerical grid of the SZ site-scale flow and transport models. Although the grid-generation and 
flow-calculation capabilities exist to do this, the need to calibrate the model efficiently and 
perform particle-tracking transport simulations has taken priority and led to the adoption of 
structured grids that make explicit inclusion of faults difficult. Important faults are included in 
the model to capture their impact on flow and transport. Furthermore, the adoption of a range 
that includes larger specific discharge values and smaller effective porosities introduces 
realizations that replicate the behavior of a fault-dominated flow and transport system. 
Therefore, the suite of performance assessment transport simulations currently used likely 
encompasses the range of behavior that will be obtained with a fault-based flow and transport 
model. 
6.8.6 Scaling Issues 
Scaling issues are some of the most complex modeling problems to overcome, and it is an active 
field of contemporary research in geohydrology (Neuman 1990 [DIRS 101464]). Although there 
are many approaches that address the effects of scaling on model results, none has been widely 
accepted as the best method. Transport models are particularly sensitive to scaling issues in 
both space and time. For example, distribution coefficients measured on the order of hours to 
months in the laboratory for a performance assessment model are dubiously applied to transport 
of contaminants over millennia. However, flow modeling is much less sensitive to scaling issues 
in both space and time. First, time scales are relatively unimportant because hydrogeologic 
properties change little over the course of millennia. While waterlevel data and infiltration 
rates may change over such long time-periods, any flow model can easily account for these 
changes given appropriate boundary conditions. Second, while hydrogeologic properties 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-173 November 2004 
measured through borehole pumping tests may not be appropriate to apply at distances far from 
the sample site (distance scaling), the SZ site-scale flow model described here does not use these 
measured properties directly. Instead, they are used as calibration targets and to describe 
parameter estimation limits. Therefore, although it may be inappropriate to assign geologic 
properties based on distant measurements, the calibration techniques used in this SZ site-scale 
flow model moderate the negative impact of such scaling issues. 
6.8.7 Description of Barrier Capability 
This model report is a compilation of information and processes affecting flow in the SZ around 
Yucca Mountain. As such, it provides a description of the SZ barrier flow component. The two 
main features of the barrier described here are: (1) the specific discharge, which affects the 
transport time of the radionuclides that may be released at the water table beneath the repository 
horizon and travel to the accessible environment; and (2) the flow paths that will affect the travel 
length and, therefore, transport times. 
The base case result for specific discharge ranges from 0.5 m/yr to 3 m/yr, depending on the part 
of the flow path. The average particle flow path itself is likely to travel southeast as it leaves the 
repository area and follow Fortymile Wash, where it encounters large amounts of alluvial 
material. Transport times are expected in the thousands of years (BSC 2004 [DIRS 170042], 
Sections 6.6 and 6.7). 
Uncertainty affects the permeability range and the flow paths. These parameters, with the head 
gradient, comprise the components of the specific discharge calculations. The largest uncertainty 
range for permeability was that of the Bullfrog Tuff in which the mean value, 1.4 x 1011 m2, 
varied by a factor of 3. The flow paths proved to be relatively independent of the ACM provided 
the moderate and low gradient observations were adequately represented in the calibrated 
numerical model. 
Outputs from this model report are used in the SZ site-scale transport model report (BSC 2004 
[DIRS 170036]) to generate both concentrations-versus-time and concentrations-versus-distance 
curves that are needed to demonstrate the capabilities of the SZ flow and the transport barrier. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 6-174 November 2004 
INTENTIONALLY LEFT BLANK 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-1 November 2004 
7. VALIDATION 
Model validation is the process of testing the appropriateness of the conceptual, mathematical, 
and numeric representation of the system being modeled. The SZ site-scale flow model is 
designed to provide an analysis tool that facilitates understanding of flow in the aquifer beneath 
and downgradient from the repository. The flow model is also a computational tool to provide 
the flow fields for performing radionuclide migration predictions in the SZ. For these 
predictions to be credible, the SZ site-scale flow model has been validated for its intended use. 
This statement means that there is established confidence that a mathematical model and its 
underlying conceptual model adequately represents with sufficient accuracy the phenomenon, 
process, or system in question. Based on the material presented in these sections, this 
requirement is considered satisfied. 
The validation criteria are provided in Section 7.1; the validation results are discussed in 
Section 7.2; and the summary of the validation effort is presented in Section 7.3. 
The data used in validation activities are discussed in the following sections and are summarized 
below. 
 Observed hydraulic heads not used for model development and calibration. This 
includes the potentiometric data not available at the time when model calibration was 
conducted (DTN: GS010908312332.002 [DIRS 163555]). 
 Hydraulic parameters derived from hydraulic testing at the C-wells, Alluvial Testing 
Complex, and single-well testing at other wells (BSC 2004 [DIRS 170010]). 
 Temperature measured in the wells (DTN: MO0102DQRBTEMP.001 [DIRS 154733]). 
 Flow paths derived from hydrochemistry and isotope analysis (Appendix A). 
7.1 VALIDATION CRITERIA 
The current Technical Work Plan For: Natural System  Saturated Zone Analysis and Model 
Report Integration (BSC 2004 [DIRS 171421], Section 2.2.1.1) states that model validation was 
completed following criteria in the previous version of the technical work plan. Model 
validation presented in Section 7 follows the Technical Work Plan for: Saturated Zone Flow and 
Transport Modeling and Testing (BSC 2003 [DIRS 166034], Section 2.5). Section 2.5 of the 
2003 technical work plan states that Level II validation will be achieved through confidence 
building during model development and implementing one or more postdevelopment validation 
methods. In the case of the SZ site-scale flow model, the chosen postdevelopment method was 
the corroboration of the model results to observed data on waterlevel elevation, permeability 
and specific discharge data, temperature data, and flow paths interpreted from geochemistry and 
isotope data. 
The acceptance criteria for validation of the SZ site-scale flow model are the following: 
 A favorable qualitative comparison between the simulated SZ flow paths and those 
deduced from the hydrochemistry and isotope data. The flow paths simulated by the SZ 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-2 November 2004 
site scale flow model are enveloped by those deducted from the hydrochemical and 
isotope data. 
 A favorable quantitative comparison of: 
- Model simulated waterlevel data with observed waterlevel data 
- Model simulated temperature data and observed temperature data 
- Calibrated permeability data and data obtained from field and laboratory testing 
- Model simulated specific discharge and those derived from field-testing data. 
These acceptance criteria reflect the essential functions of the SZ system with regard to the 
transport time and radionuclide mass delivery to the accessible environment. 
7.1.1 Confidence Building During Model Development to Establish Scientific Basis and 
Accuracy for Intended Use 
For Level II validation, the development of the model should be documented in accordance with 
the requirements of Section 5.3.2(b) of AP-SIII.10Q. The development of the SZ site-scale flow 
model was conducted according to the following criteria (italicized). The paragraphs following 
each criterion describe how it was satisfied. 
1. Selection of input parameters and/or input data, and a discussion of how the selection 
process builds confidence in the model [AP-SIII.10Q, 5.3.2(b)(1) and AP-2.27Q 
Attachment 3, Level I (a)]. 
The inputs to the SZ site-scale flow model have all been obtained from controlled sources (see 
Table 4-1). Model assumptions have been described in Section 5. Detailed discussion about 
model concepts can be found in Section 6.3. Further studies of flow based on field observations 
are presented in Section 7, leading to increased confidence in the parameters that are used in the 
SZ site-scale flow model presented in this report. Two assumptions were made in Section 5: 
(1) concerning vertical to horizontal anisotropy and (2) concerning homogeneous representation 
of hydrogeologic properties for all units. 
2. Description of calibration activities, and/or initial boundary condition runs, and/or 
run convergences, simulation conditions set up to span the range of intended use and 
avoid inconsistent outputs, and a discussion of how the activity or activities build 
confidence in the model. Inclusion of a discussion of impacts of any nonconvergence 
runs [(AP-SIII.10Q 5.3.2(b)(2) and AP-2.27Q Attachment 3 Level I (e)]. 
The SZ site-scale flow model uses the waterlevel potentiometric surface (BSC 2004 
[DIRS 170009]) as a starting point. The model was calibrated to waterlevel 
elevations measured from 114 wells. Recharge and lateral boundary fluxes were 
developed from the DVRFS flow model and the UZ site-scale flow model (Section 
6.3) Initial conditions were not required for the steady state model. Sections 6.6 and 
6.7 provide detailed discussion of various model results (i.e., those of convergence 
runs). All runs discussed in this report have converged. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-3 November 2004 
3. Discussion of the impacts of uncertainties to the model results including how the 
model results represent the range of possible outcomes consistent with important 
uncertainties [(AP-SIII.10 Q 5.3.2(b)(3) and AP-2.27Q Attachment 3 Level 1 (d) 
and (f)]. 
A discussion of model uncertainties is provided in Section 8.3. Sensitivity of the 
output (specific discharge and flow paths) to each of the uncertain input parameters is 
discussed in Sections 8.3.1 through 8.3.2. 
4. Formulation of defensible assumptions and simplifications [AP-2.27Q Attachment 3 
Level I (b)]. 
Discussion of assumptions and simplifications are provided in Sections 5 and 6.3. The 
conceptual model of flow in the SZ and the components of the model are discussed in 
Section 6.3. As discussed in detail in Section 7, further confidence building in 
submodel components of the SZ site-scale flow model was conducted through 
comparison of the conceptual model of SZ flow with the results of field tests 
conducted at the C-wells complex, the ATC. These following observations were made 
from testing at both the C-wells and ATC regarding the two assumptions: 
 Testing at the ATC indicated that hydrogeologic properties could be represented as 
homogeneous values. 
 Testing at the C-wells indicated that the volcanic tuffs are a fractured dominated 
system. 
Long term testing resulted in responses that could be fitted with effective continuum 
physical equations and homogeneous hydrologic properties. Thus, this requirement is 
considered satisfied. 
5. Consistency with physical principles, such as conservation of mass, energy, and 
momentum [AP-2.27Q Attachment 3 Level I (c)] 
Consistency with physical principles is demonstrated by the conceptual and 
mathematical formulation in Sections 6.3 and 6.5, and the selection and use of the 
FEHM Code in Section 3. The governing equations for nonisothermal flow 
implemented in FEHM are based on conservation of mass and energy and Darcys 
law. As discussed in detail in Section 7.2 further confidence building in the SZ 
site-scale flow model was conducted through comparison of the conceptual model of 
SZ flow and model results with the results of field tests conducted at the C-wells 
complex and the ATC. Testing at the C-wells indicated that: 
 The volcanic tuffs are a fractured dominated system. 
 Long term testing resulted in responses that could be fitted with effective continuum 
physical equations and homogeneous hydrologic properties. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-4 November 2004 
 The testing at the ATC confirmed that the flow system behaves as a porous media. 
These tests therefore validated that the SZ can be modeled as an effective continuum 
with homogeneous properties. Thus, this requirement is considered satisfied. 
7.1.2 Confidence Building After Model Development to Support the Scientific Basis of 
the Model 
Model validation requires mathematical models be validated by one or more of several methods 
given in Section 5.3.2(c and d) of AP-SIII.10Q [DIRS 171760]. Validation of the SZ site-scale 
flow model is documented in Section 7 of this report and is related to the procedural 
requirements as follows. 
1. AP-SIII.10Q 5.3.2(c), Method 1: Corroboration of model results with the 
laboratory, field experiments, analog studies, or other relevant observations, not 
previously used to develop or calibrate the model. 
The SZ site-scale flow model was validated by comparing results from this model 
with the laboratory and field experiment and other observations. The validation 
criteria, testing, and results are described in detail in Section 7.2 of this report. 
Based on material presented in these sections this requirement is considered 
satisfied. 
2. AP-SIII.10Q 5.3.2(d): Technical review through publication in a refereed 
professional journal. Although this is not required by the TWP, this post 
development validation activity adds to the confidence in the SZ site-scale flow 
model. 
The SZ site-scale flow model and its results are described in the referenced 
professional publications of Eddebbarh et al. (2003 [DIRS 163577]) and 
Zyvoloski et al. [(2003 [DIRS 163341]). These publications demonstrate 
additional confidence in the model, when taken in conjunction with the model 
validation activity described in item 1 above. 
7.2 VALIDATION RESULTS 
The validation activities for the SZ site-scale flow model are carried out according to the 
Technical Work Plan for: Natural System - Saturated Zone Analysis and Model Report 
Integration (BSC 2004 [DIRS 170115]), Section 2.2), which requires Level II model validation 
of the SZ site-scale flow model based on its relative importance to the performance of the 
repository system. The technical work plan states that the validation activities will include 
confidence building activities implemented during model development. In addition, the 
technical work plan states that postmodel development validation will consist of a comparison of 
simulated flow paths with those derived from hydrochemistry and isotope analyses, plus one or 
more other comparisons as indicated in the technical work plan. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-5 November 2004 
The following comparisons were completed between: 
 Predicted and observed hydraulic heads not used during model development and 
calibration, including recently available potentiometric data. 
 Simulated and observed hydraulic properties. These include permeability and hydraulic 
gradient. At locations where sufficient new data are available, the validation has been 
extended to a comparison of the specific discharge calculated using predicted and 
observed values of both hydraulic gradient and permeability. Observed specific 
discharge is deduced (1) from permeability data derived from hydraulic testing at 
locations where the hydraulic data and resulting parameter values were not used during 
model development and calibration, and (2) ATC tracer test results. Simulated specific 
discharges are deducted from calibrated hydraulic conductivity and simulated hydraulic 
gradient. 
 Flow path derived from hydrochemistry and isotope analysis and those predicted by the 
SZ site-scale flow model. 
 Predicted and observed temperatures in SZ wells. A thermal model based on the SZ 
site-scale flow model is used to predict temperatures in the SZ wells. 
For purposes of postmodel development validation, a comparison of predicted and observed 
water levels for all the new water level data is presented in Section 7.2.1. This comparison 
focuses on the Phase II water level data obtained as part of the Nye County Early Warning 
Drilling Program (NC-EWDP) (DTN: MO9909NYEEWDP0.000 [DIRS 119613. A comparison 
of predicted and observed gradients along the flow path from the repository is also presented to 
evaluate the impact of the difference between observed and predicted water levels on the 
computation of specific discharge. Specific discharge is directly proportional to the hydraulic 
gradient. As previously established in the SZ technical work plan (BSC 2004 [DIRS 170115], 
Section 2.2), validation is considered acceptable if the differences between simulated and 
observed hydraulic gradients are not greater than 50 percent of the observed hydraulic gradient 
along the flow path from the water table directly beneath the repository to the compliance 
boundary at the accessible environment (differences may be greater than 50 percent away from 
this flow path). The 50 percent criterion used here is within the range (a factor of 3 smaller or 
larger) used for representing uncertainty in the specific discharge for calculations used directly 
by TSPA. 
The comparison of specific discharges based on calibrated hydraulic parameters (permeability 
values) and those derived from hydraulic testing is presented in Section 7.2.2. This section 
summarizes the data from Yucca Mountain and nearby areas available for determining the 
permeability of the hydrogeologic units represented in the SZ site-scale flow model. These data 
are compared to the permeability values established during the calibration of the SZ site-scale 
flow model. However, because the permeability data were used to constrain permeability 
parameters during model calibration, the comparisons are not suitable for formal, postmodel 
development validation. Rather, these comparisons are provided in support of model validation 
as a confidence-building activity. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-6 November 2004 
New permeability measurements are available from the Alluvial Testing Complex (BSC 2004 
[DIRS 170010], Section 6). These permeability measurements were not used during model 
development and calibration and, as such, are suitable for postmodel development validation. 
The measurements were taken along the flow path from the repository. Section 7.2.2 compares 
these measurements with calibrated permeabilities. In addition, because new waterlevel data 
and permeability measurements are available at the ATC, predicted and observed values of 
hydraulic gradient and permeability at this location are used to calculate specific discharge. 
These calculated values are compared to the model-simulated specific discharge for the test 
location for purposes of postmodel development validation. Furthermore, the ATC tracer test 
also independently provides estimates of specific discharge from groundwater flow velocity for a 
range of flowing porosity (DTN: LA0303PR831231.002 [DIRS 163561]; BSC 2004 
[DIRS 170010], Section 6.4); a comparison also was made between the calibrated and the testderived 
specific discharge values at the ATC. As previously established in the SZ technical 
work plan (BSC 2004 [DIRS 170115], Section 2.2), validation is considered acceptable if the 
differences between specific discharge values are within the factor of 3 used in TSPA 
simulations. 
The comparison of the predicted flow pathways with those derived from the hydrochemistry and 
isotope analysis is presented in Section 7.2.3. The hydrochemistry and isotope analysis was not 
used during model development and calibration and, consequently, is suitable for post-model 
development validation. The flow-path comparison is considered acceptable if the flow paths 
predicted by the model are enveloped by those flow paths inferred from hydrochemical and 
isotope analyses (Appendix A). 
The comparison of predicted and observed temperatures in SZ wells is presented in 
Section 7.2.4. A thermal model based on the SZ site-scale flow model is used to predict 
temperatures in the SZ wells. This validation method involves the evaluation of the models 
ability to simulate the magnitudes and spatial distribution of temperature differences observed in 
wells in the SZ. This activity constitutes postmodel development validation of the SZ site-scale 
flow model because the temperature data represent an independent data set that was not used in 
construction or calibration of the model. The validation criteria consist of a quantitative 
comparison between the measured and simulated temperatures in wells and qualitative 
comparison of spatial patterns for observed wells (BSC 2004 [DIRS 171421], Section 2). The 
calibration target of 10C was selected because of the wide range of temperature variations 
observed in the SZ near Yucca Mountain. 
7.2.1 Comparison of Observed and Predicted Nye County Water Levels 
Since the calibration of the SZ site-scale model, 15 additional wells have been installed as part of 
the Nye County EWDP. These additions include wells installed at new locations and wells 
completed at depths different from those previously available at existing locations. Comparison 
of the water levels observed in the new Nye County EWDP wells with water levels predicted by 
the SZ site-scale flow model at these new locations and depths offers an opportunity to validate 
the model. In addition, water-level measurements from the new Nye County EWDP wells 
provide additional data for use in comparing the measured and predicted hydraulic gradients 
along the flow path from the repository. This comparison can be used to validate the SZ 
site-scale model quantitatively. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-7 November 2004 
The SZ site-scale model was calibrated using 114 water level and head measurements from wells 
within the model domain, as described in Section 6.6.1.3. Eight of these measurements were 
from wells drilled and completed as part of the Nye County EWDP. Measured and predicted 
heads for these wells, along with their coordinates, are shown in Table 7-1. The locations of 
these wells are shown in Figure 7-1. 
Table 7-1. Nye County EWDP Wells Used as Calibration Targets in the Saturated Zone Site-Scale 
Model Calibration with Observed and Predicted Water Levels 
Well ID 
Easting 
(UTM) 
(m) 
Northing 
(UTM) 
(m) 
z (elevation) 
(m) 
Observed 
Head (m) 
Modeled 
Head 
(m) 
Residual 
Error (m) 
NC-EWDP-1DX 
shallow 
536768 4062502 413.5 786.8 763.9 -22.9 
NC-EWDP-1S 
probe 1 
536771 4062498 747.8 787.1 773.3 -13.8 
NC-EWDP-2D 547744 4057164 507.2 706.1 709.3 -3.2 
NC-EWDP-3D 541273 4059444 376.7 718.3 703.9 -14.4 
NC-EWDP-3S 
probe 2 
541269 4059445 719.1 719.8 702.5 -17.3 
NC-EWDP-5SB 555676 4058229 603.9 723.6 718.0 -5.6 
NC-EWDP-9SX 
probe 2 
539039 4061004 721.2 767.3 732.5 -34.8 
NC-Washburn- 
1X 
551465 4057563 668.8 714.6 714.6 0.0 
Source DTN: GS010908312332.002. (DIRS 163555). 
UTM = Universal Transverse Mercator 
Source DTN: GS010908312332.002 [DIRS 163555] (coordinates for well locations). 
NOTE: The coordinates for well locations can be found in Table 7-2. UTM = Universal Transverse Mercator 
Figure 7-1. Locations of Nye County EWDP Wells 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-8 November 2004 
With the addition of the new EWDP wells, the number of waterlevel observations available in 
the Nye County area has increased to 26. These wells are identified in Table 7-2, and the 
location of these wells is shown in Figure 7-1. As indicated in Table 7-2, waterlevel data from 
new completion intervals at previously existing well locations are now available and, for the 
purpose of this comparison, are replacing water levels previously available at this location. It 
should also be noted that although NC-EWDP-2D, NC-EWDP-3D, and NC-Washburn-1X were 
previously used as calibration targets for the SZ site-scale model, water levels from these wells 
are included in Table 7-2. All these wells were assigned the same weight equal to 1. 
Examination of the residuals reported in Table 7-2 indicates that the errors in predicted water 
levels are highly dependent on their location within the site-scale model domain. Well clusters 
NC-EWDP-1, -9, and -12 are in the western portion of the Nye County study area, along 
U.S. Highway 95 and south of Crater Flat. The residuals observed in this cluster range from 
+13.9 m to -35.6 m. Comparing Figure 6-3 and Figure 7-1 shows that these wells are located in 
an area of rapid waterlevel changes, along the U.S. Highway 95 fault, and the model is not able 
to replicate fully the steep head gradients observed in this area. Similar residual errors were 
observed using the waterlevel data available during model calibration. The new data indicate 
significant vertical gradients at the NC-EWDP-1 well cluster, which the calibrated model is not 
able to reproduce. NC-EWDP-7S is located north of these wells. The residual observed here 
was -60.5 m, but this well is located on a paleospring deposit at the southern end of Crater Flat. 
All of these wells are located in the southern portion of the Crater Flat flow system. 
Consequently, the errors observed in this area of the model domain are not likely to influence 
significantly the flow system from the repository. A residual of -19.9 m was also observed for 
well NC-EWDP-1P, which is located northeast of well NC-EWDP-7S in the lower Solitario fault 
area. This area is also one of significant water level change. 
Table 7-2. Comparison of Water Levels Observed and Predicted at Nye County EWDP Wells 
Site Name 
Easting (UTM) 
(m) 
Northing 
(UTM) 
(m) 
z (elevation) 
(m) 
Observed 
Head (m) 
Modeled 
Head (m) 
Residual 
Error (m) 
NC-EWDP-1DX, shallow 536768 4062502 585.7 786.8 756.7 -30.1 
NC-EWDP-1DX, deep 536768 4062502 133.1 748.8 762.7 13.9 
NC-EWDP-1S, P1 536771 4062498 751.8 787.1 767.3 -19.8 
NC-EWDP-1S, P2 536771 4062498 730.8 786.8 767.3 -19.5 
NC-EWDP-2DB 547800 4057195 -77.0 713.3 717.0 3.7 
NC-EWDP-2D 547744 4057164 507.1 706.1 709.2 3.1 
NC-EWDP-3D 541273 4059444 377.9 718.3 703.7 -14.6 
NC-EWDP-3S, P2 541269 4059445 682.8 719.8 702.5 -17.3 
NC-EWDP-3S, P3 541269 4059445 642.3 719.4 702.6 -16.8 
NC-EWDP-5SB 555676 4058229 707.8 723.6 718.0 -5.6 
NC-EWDP-9SX, P1 539039 4061004 765.3 766.7 731.7 -35.0 
NC-EWDP-9SX, P2 539039 4061004 751.3 767.3 731.7 -35.6 
NC-EWDP-9SX, P4 539039 4061004 694.8 766.8 731.7 -35.1 
NC-Washburn-1X 551465 4057563 687.0 714.6 714.5 -0.1 
NC-EWDP-4PA 553167 4056766 687.0 717.9 715.5 -2.4 
NC-EWDP-4PB 553167 4056766 582.5 723.6 715.5 -8.1 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-9 November 2004 
Table 7-2. Comparison of Water Levels Observed and Predicted at Nye County EWDP Wells 
(Continued) 
Site Name 
x (UTM) 
(m) 
y (UTM) 
(m) 
z (elevation) 
(m) 
Observed 
Head (m) 
Modeled 
Head (m) 
Residual 
Error (m) 
NC-EWDP-7S 539638 4064323 826.6 830.1 769.6 -60.5 
NC-EWDP-12PA 536951 4060814 666.7 722.9 705.3 -17.6 
NC-EWDP-12PB 536951 4060814 666.7 723.0 705.3 -17.7 
NC-EWDP-12PC 536951 4060814 713.7 720.7 704.3 -16.4 
NC-EWDP-15P 544848 4058158 716.9 722.5 711.0 -11.5 
NC-EWDP-19P 549329 4058292 694.7 707.5 713.2 5.7 
NC-EWDP-19D 549317 4058270 549.7 712.8 713.2 0.4 
DTN: GS010908312332.002 [DIRS 163555] (first five columns); 
Output DTN: LA0304TM831231.002. 
NOTE: z-elevation refers to the mid point of the monitored open interval of an uncased well. UTM = Universal 
Transverse Mercator 
The observed residuals tend to improve as the wells are located further to the east. The residual 
errors at the NC-EWDP-3 well cluster range from -14.6 m to -17.3 m. With an observed residual 
of -11.5 m at NC-EWDP-15P, the residuals decrease in well locations further east. At the 
NC-EWDP-19 cluster location (the ATC), the residuals improve further, with observed values of 
only +0.4 m and +5.7 m. The residuals in this general area at NC-Washburn-1X, NE-EWDP-4, 
and NC-EWDP-5 are similarly low. These wells are in the predicted flow path from the 
repository. Thus, these additional waterlevel data confirm the SZ site-scale models capability 
to predict water levels accurately in this portion of the flow path from the repository. 
To further validate the SZ site-scale flow model, a comparison of the hydraulic gradients along 
the flow path from the repository observed through field data and predicted by the model has 
been performed. These gradients have a direct impact on the prediction of specific discharge 
along the flow path from the repository and can be used to determine whether the model meets 
the validation criterion of having an effect not greater than 50 percent on the specific discharge. 
The waterlevel data from a series of six wells extending from the immediate area of the 
repository to the new Nye County EWDP well 19P is presented in Figure 7-2. The predicted and 
observed hydraulic gradient among the identified wells is presented in Table 7-3. The location 
of these wells is shown in Figures 6-40 and Figure 7-1. Only the hydraulic gradient calculated 
for the last segment actually involves new waterlevel data not previously used during the SZ 
site-scale flow model development and calibration. Consequently, only a comparison of 
predicted and observed hydraulic gradients from this segment meets the requirement of 
postmodel development validation. The comparison of predicted and observed hydraulic 
gradients along the remainder of the flow path from the repository is presented as a 
confidence-building activity. 
As Figure 7-2 and Table 7-3 indicate, the observed and predicted gradients along the flow path 
are in good agreement, except in the northernmost part of the flow path. The wells were selected 
because they were on or close to the predicted flow path and included wells that were on the east 
and west of the Solitario Canyon fault. Another candidate well not selected, H-5, is discussed in 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-10 November 2004 
Section 6.6.2.1. The discrepancies in water levels observed and predicted between wells H-6 and 
WT-2 are the result of the manner in which the model accounts for the effect of the splay of the 
Solitario Canyon fault, which lies in the general area of these wells. However, while the model 
does not accurately predict the precise location for the drop in head across the fault, largely 
because of the 500-m grid blocks, the overall hydraulic gradient predicted between H-6 and 
WT-2 agrees reasonably well with the value (34 percent). Regarding the segment between WT-2 
and WT-1, for which simulated hydraulic gradient differs from the observed by 60 percent, in 
absolute terms the difference between the observed and simulated hydraulic gradients is very 
close to zero. The water table is very flat in that area, and the accuracy of land surface altitude is 
0.1 m BSC 2004 [DIRS 170009]). Overall, the comparisons between simulated and observed 
hydraulic gradients along the flow path are deemed acceptable and in compliance with the 
50 percent validation criterion of the 2003 technical work plan (BSC 2004 [DIRS 171421], 
Section 2.2). 
7.2.2 Comparison of Specific Discharge Based On Permeability Data and Alluvial 
Testing Complex Tracer Test Results 
The numerical model was calibrated by adjusting permeability values for individual 
hydrogeologic units in the model until the sum of the weighted-residuals squared (the objective 
function) was minimized. The residuals include the differences between the measured and 
simulated hydraulic heads and the differences between the groundwater fluxes simulated with the 
regional- and the site-scale models. Permeabilities estimated from hydraulic tests were neither 
formally included in the calibration as prior information nor were considered in the calculation of 
the objective function. The field-derived permeabilities were instead used to guide the selection 
of bounds on the permissible range of permeabilities to be considered during the calibration and 
to check on the reasonableness of the final permeability estimates produced by the calibration. 
However, since these permeability data were used to constrain permeability parameters during 
model calibration, these measurements are not suitable for formal postmodel-development 
validation. Rather, they are presented and discussed below in support of model validation as a 
confidence-building activity. New permeability measurements are available from the ATC. 
These permeability measurements were not previously used during model development and 
calibration and, as such, are suitable for postmodel-development validation. A comparison of 
calibrated permeability values with those newly obtained values from the ATC is presented 
below. The impact of the differences between these values on the determination of specific 
discharge is also evaluated. In addition, an analysis of the combined impact of differences 
between predicted and observed hydraulic gradients and permeabilities at the ATC on specific 
discharge is presented below. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-11 November 2004 
Source DTN: GS000508312332.001 [DIRS 149947]. Output DTN: LA0304TM831231.002. 
NOTE: Data results computed from Table 6-20. 
UTM = Universal Transverse Mercator 
Figure 7-2. Measured and Simulated Head Along Flow Path 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-12 November 2004 
Table 7-3. Predicted and Observed Hydraulic Gradient for Identified Wells 
Flow Segment .H/.L (Measured) .H/.L (Simulated) 
H-6 to WT-2 0.0118 0.0078 
WT-2 to WT-1 0.000094 0.00015 
WT-1 to WT-3 0.00021 0.00021 
WT-3 to 19P/2D 0.0015 0.0016 
DTN: GS000508312332.001 [DIRS 149947]. 
Source Output DTN: LA0304TM831231.002. 
NOTE: Data results computed from Table 6-20. 
Discussions of the permeability data from the Yucca Mountain Area and nearby NTS as well as 
the Apache Leap site in Arizona are presented in the following subsections. A discussion of the 
general inferences about permeability that can be drawn from regional observations is also 
presented. Following these discussions, a comparison of calibrated with measured permeability 
values is presented, including the analysis of the potential impact of calibrated permeability 
values on groundwater specific discharge. 
In the following discussion, the permeability values will be cited with 10-12 m2 as the base 
exponent for comparison purposes. 
7.2.2.1 Newer Permeability Data 
Information contained in Section 7.2.2.1 was acquired or accepted since the calibration of the SZ 
site-scale flow model. 
Many factors can be expected to affect the permeability of the volcanic rocks at Yucca 
Mountain, including: (1) the tendency of the rock either to fracture or to deform plastically in 
response to stress; (2) the ability of the rock to maintain open fractures, which is a function of the 
strength of the rock and overburden stress; (3) proximity to major zones of deformation, such as 
fault zones; and, (4) the degree of mineralization or alteration that would tend to seal fractures 
and faults. Other factors being equal, rocks that tend to fracture are at shallow depth, have high 
compressive strength, are located in a fault zone, or are unmineralized and would be expected to 
have high permeabilities compared to rocks that do not possess these attributes. In addition to 
actual variations in permeability, the scale of measurement may also influence the permeability 
value determined by a test. This effect is most often observed when results of permeability tests 
conducted on cores that do not contain fractures are compared to the results of tests conducted in 
boreholes that contain fractured intervals. At Yucca Mountain, the relatively high permeabilities 
estimated from cross-hole tests compared to single-hole tests in the same rock unit have also 
been attributed to the effects of scale (Geldon et al. 1998 [DIRS 129721]). In this case, the cause 
of the permeability increase in the cross-hole tests is attributed to the greater likelihood of 
including relatively rare but highly transmissive and continuous features in the larger rock 
volume sampled by the cross-hole tests. This assumption is reevaluated below based on recent 
analyses of air-injection tests conducted at the Apache Leap test site near Globe, Arizona. 
Permeability data from single- and multiple-borehole hydraulic tests at Yucca Mountain and 
single-borehole tests elsewhere at the NTS have been compiled and compared to permeabilities 
estimated during calibration of the SZ site-scale flow model. Several aspects of the data merit 
further discussion. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-13 November 2004 
7.2.2.1.1 Calico Hills 
First, the mean permeability estimated for the Calico Hills Formation from single-hole tests 
(k = 7.8 x 1014 m2) is of the same order as that estimated from cross-hole tests (k = 1.7 x 
10-13 m2). This observation indicates that factors other than the test method and the scale of the 
test are influencing results. One such factor may be proximity to faults. Several of the 
single-hole tests conducted in the Calico Hills Formation were performed in the highly faulted 
area near borehole UE-25 b#1, whereas faults were present only at deeper stratigraphic horizons 
at the C-wells where the cross-hole tests were done (Geldon et al. 1998 [DIRS 129721], 
Figure 3). Nonetheless, geologic contacts with open partings may also have enhanced 
permeability in the Calico Hills Formation at the C-wells (Geldon et al. 1998 [DIRS 129721], 
Figure 5). Second, both estimates of the mean Calico Hills Formation permeability are either 
larger than the mean permeability estimated for the carbonate aquifer from Yucca Mountain data 
(k = 0.072 x 10-12 m2) or comparable to mean permeabilities estimated for the carbonate aquifer 
from data elsewhere at the NTS (k = 0.6 x 1012 m2). Although the permeability of the Calico 
Hills Formation may be locally higher than the mean permeability of the carbonate aquifer, it is 
unlikely that this relation between the two formation permeabilities can exist in general. The 
carbonate aquifer, along with the alluvial aquifers, is widely viewed as a major water-supply 
source in Southern Nevada (Dettinger 1989 [DIRS 154690]). In contrast, the Calico Hills 
Formation has properties similar to those of rocks deemed suitable for nuclear weapons tests 
below the water table at Pahute Mesa. The rocks at Pahute Mesa had properties (low intrinsic 
permeability due to zeolitization and sparse, poorly connected fractures) that were predicted, and 
later observed, to result in only small amounts of seepage into open test chambers during their 
construction (Blankennagel and Weir 1973 [DIRS 101233], pp. B30 to B31). Similar rocks in 
the unsaturated zone at Rainier Mesa produced perched water from isolated fault zones during 
construction of tunnels into the mesa; however, because the fault zones drained quickly and fault 
zones intersected later during tunneling also initially produced water, the fault zones were 
inferred to be relatively isolated both horizontally and vertically (Thordarson 1965 
[DIRS 106585], pp. 42 to 43). At Yucca Mountain, the apparently widespread presence of 
perched water on top of the zeolitic Calico Hills Formation in northern Yucca Mountain 
(Patterson 1999 [DIRS 158824]) indicates that the formation generally has low permeability 
compared to the rate of water percolation through the unsaturated zone, which has been 
estimated to average 1 mm/yr to 10 mm/yr in the vicinity of the repository under the present 
climate (Flint 1998 [DIRS 100033]). Water flowing under a unit gradient at a rate of 10 mm/yr 
(3.17 x 1010 m/s) would pass through a rock having a permeability of 3.23 x 1017 m2 (assuming 
a viscosity of 0.001 N-s/m2 and a water density of 1000 kg/m3); so the field-scale vertical 
permeability of the Calico Hills Formation, which includes the effects of fracturing, presumably 
has permeabilities less than this value. The geometric-mean hydraulic conductivity for the 
zeolitic Calico Hills Formation, based on core measurements, is 4.5 x 10-11 m/s (Flint 1998 
[DIRS 100033], Table 7), comparable to the low hydraulic conductivity value (3.231017 m2) 
previously thought as necessary for perched water. 
7.2.2.1.2 Alluvial Testing Complex 
From July through November 2000, pumping tests were conducted in well NC-EWDP-19D1. 
The first test involved production from the entire saturated thickness of 136 m (446 feet). The 
results indicated a transmissivity of about 21 m2/day (223 ft2/day) and an average hydraulic 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-14 November 2004 
conductivity of 0.5 ft/day, approximately equivalent to a permeability of 0.2 x 1012 m2. 
Subsequently, four screened intervals having a combined thickness of 84 m (276 f t) were tested 
individually. The combined transmissivities of these intervals totaled about 145 m2/day 
(1,600 ft2/day), far exceeding the transmissivity determined for the initial open-hole test. There 
are at least two likely causes for the discrepancy. First, pumping apparently resulted in further 
well development, as fine materials were drawn into the well and discharged with the water. 
Second, the screened intervals are probably interconnected hydraulically, consistent with the 
complexity of fluvial-alluvial depositional environments, so that actual thicknesses of the 
producing zones were significantly greater than the screened intervals. The average permeability 
of the section is probably greater than the initial permeability determined from the open-hole test 
(0.2 x 1012 m2) but less than those calculated for the two deeper screened intervals, 
1.5 x 10-12 m2 and 3.3 x 1012 m2. Although thin, discontinuous zones may locally have higher 
permeabilities, these results indicate that significantly thick (greater than 10 m) and areally 
extensive zones at NC-EWDP-19D1 probably have average permeabilities between 
0.1 x 10-12-1 x 1012 m2. 
7.2.2.1.3 Apache Leap 
Fractured welded tuffs and relatively unfractured nonwelded tuffs occur both above and below 
the water table. Permeabilities measured in the unsaturated zone at Yucca Mountain using air 
may, therefore, have some relevance to the permeability values of similar rocks located below 
the water table. In the unsaturated zone, air-injection tests have been conducted from 
surface-based boreholes in both welded and nonwelded tuffs (LeCain 1997 [DIRS 100153]) and 
from test alcoves in and adjacent to the Ghost Dance fault zone in the densely welded Topopah 
Spring tuff (LeCain et al. 2000 [DIRS 144612]). At Yucca Mountain, no water-injection tests 
were done in these same intervals to directly compare to the results of the air-injection tests. 
However, some understanding of the probable relation between permeabilities estimated from 
air- and water-injection tests at Yucca Mountain can be made on the basis of tests in nonwelded 
to partially welded tuff at the Apache Leap experimental site in Arizona, where borehole air- and 
water-injection tests were made at ambient moisture conditions in the same depth intervals 
(Rasmussen et al. 1993 [DIRS 154688]). The Apache Leap data (Rasmussen et al. 1993, 
Figure 5b [DIRS 154688]) showed a somewhat complex relation between permeabilities 
calculated from the two types of tests. Air-injection tests resulted in lower permeabilities than 
water-injection tests in borehole intervals for which permeabilities calculated using both fluids 
indicated that fractures were sparse or absent. In these intervals, matrix pore water probably 
obstructed air movement. However, in test intervals for which air and water permeabilities were 
both relatively high, the air-injection tests resulted in permeabilities comparable to or higher than 
permeabilities from the water-injection tests. In these intervals, both fluids probably moved into 
drained fractures. Additionally, because gravitational influences on air are not as pronounced as 
for water in the unsaturated zone, air had more possible pathways for movement than water, so 
air permeabilities were often higher than water permeabilities. Overall, the correlation between 
air and water permeabilities from the borehole injection tests at Apache Leap was r = 0.876 
(Rasmussen et al. 1993 [DIRS 154688], Figure 5b). 
The test data from Apache Leap indicate that permeabilities calculated from air-injection test 
data in the unsaturated zone at Yucca Mountain probably provide good approximations to the 
water permeabilities, particularly in the densely welded intervals where drained fractures 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-15 November 2004 
dominate the overall air permeability. The surface-based tests in four boreholes at 
Yucca Mountain showed that the highest air permeabilities (up to 54.01012 m2) were present at 
depths less than 50 m in the Tiva Canyon tuff, presumably because low lithostatic stresses at 
these depths allowed fractures to open (LeCain 1997 [DIRS 100153], Figures 7 to 10). 
However, permeabilities in the Tiva Canyon tuff typically decreased rapidly with depth, so that 
the permeabilities at depths greater than 50 m were less than 1011 m2. The geometric-mean 
permeabilities of the Tiva Canyon tuff in the four boreholes varied between 3.41012 m2 and 
8.410-12 m2 (LeCain 1997 [DIRS 100153], Table 1), with an overall geometric-mean 
permeability of 4.71012 m2 based on a total of 23 tests. Geometric-mean permeabilities of the 
Topopah Spring tuff at the four boreholes varied between 0.31012 m2 and 1.71012 m2 
(LeCain 1997 [DIRS 100153], Table 5) with an overall geometric-mean permeability of 
0.7510-12 m2 based on the results of 153 tests. 
Recent work by Vesselinov et al. (2001 [DIRS 154706]) at the Apache Leap site has 
demonstrated that permeabilities determined from multiple single-well air-injection tests and 
simultaneous numerical inversion of multiple cross-hole air-injection tests provided comparable 
estimates of the mean permeability of the test volume. However, when the cross-hole tests were 
analyzed individually with an approach equivalent to type-curve analyses, which requires the 
assumption of a uniform permeability field and a particular flow geometry (spherical), the 
resulting mean permeability estimated for the test volume was several orders of magnitude 
higher than the mean permeability estimated from the single-hole analyses or the more detailed 
simultaneous numerical inversion of the cross-hole tests. The simultaneous numerical inversion 
of the cross-hole tests did result in larger calculated variance in permeabilities than was 
estimated from the multiple single-hole tests, a result that may have been caused by round-off 
error associated with the numerical inversion. The conclusions of this work relevant to the 
present analysis are that the mean permeabilities would not be a function of test methodology 
(single-hole or cross-hole analyses) except for the inability of standard cross-hole type-curve 
methods to account for heterogeneity and departures of the actual flow field from the assumed 
flow geometry. 
7.2.2.1.4 Ghost Dance Fault 
Cross-hole air-injection tests conducted in and adjacent to the Ghost Dance fault resulted in 
geometric-mean permeability values of 4.1 x 1012 m2 for the hanging wall of the fault, 
14.6 x 10-12 m2 for the main fault zone (defined by a zone of significantly higher fracture 
density), and 7.8 x 1012 m2 for the footwall (LeCain et al. 2000 [DIRS 144612], Table 13). 
These permeabilities were higher than the permeabilities measured in the same units elsewhere 
from the surface-based boreholes and 2 to 10 times higher than the permeabilities estimated for 
the Ghost Dance fault and adjacent rock from single-hole tests conducted from an exploratory 
borehole drilled before alcove excavation (LeCain et al. 2000 [DIRS 144612], p. 26). 
Air permeabilities have also been estimated at Yucca Mountain from measured subsurface 
pneumatic pressure changes that occur in response to barometric changes at land surface 
(Kwicklis 1999 [DIRS 157414]; Ahlers et al. 1999 [DIRS 109715]). Because subsurface 
pneumatic pressure changes are described by a diffusivity equation (Weeks 1978 
[DIRS 108841]), assumptions need to be made about the effective air-filled porosity to estimate 
permeability to air. Ahlers et al. (1999 [DIRS 109715]) calculated only air diffusivity. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-16 November 2004 
Assuming the entire drained porosity of the matrix to be the effective air-filled porosity for 
airflow, Kwicklis (1999 [DIRS 157414]) estimated permeabilities for the Tiva Canyon tuff to be 
between 0.2 x 1012 m2 and 10.0 x 1012 m2 and for the Topopah Spring tuff to be between 
1.0 x 10-12 m2 and 50.0 x 1012 m2 (Kwicklis 1999 [DIRS 157414], Tables 9 to 12). The value of 
50.0 x 1012 m2 was estimated for a thin (22 m) interval at borehole NRG-6 that fracture logs 
indicated were highly fractured. Generally, however, permeabilities of about 10.0 x 1012 m2 
were adequate to match the subsurface pneumatic pressure response in the Topopah Spring tuff. 
The differences between the permeabilities obtained for the Tiva Canyon tuff and the Topopah 
Spring tuff by LeCain (1997 [DIRS 100153]) and by Kwicklis (1999 [DIRS 157414]) may be 
due to anisotropy, scale effects, or to assumptions made by Kwicklis (1999 [DIRS 157414]) 
about air-filled porosity. 
7.2.2.1.5 Tuffaceous Formations 
The Prow Pass tuff, Bullfrog tuff, and Tram tuff of the Crater Flat group contain both nonwelded 
to partially welded margins and partially to densely welded interiors (Bish and Chipera 1989 
[DIRS 101195]; Loeven 1993 [DIRS 101258]). The initially vitric nonwelded to partially 
welded margins of these units have been largely altered to zeolites during hydrothermal events as 
a result of their thermodynamically unstable glass composition and their initially high 
permeabilities (Broxton et al. 1987 [DIRS 102004]). The partially to densely welded parts of 
these units have devitrified to mostly quartz and feldspar and have higher matrix permeabilities 
than the nonwelded to partially welded zeolitized margins (Loeven 1993 [DIRS 101258]; Flint 
1998 [DIRS 100033]). Additionally, because the welded parts of the tuffs have a greater 
tendency to fracture, the densely welded parts of these units generally have higher secondary 
permeability. Thus, unless faults are locally present, the densely welded parts of the Prow Pass 
tuff, Bullfrog tuff, and Tram tuff are expected to have substantially higher permeability than the 
nonwelded margins. 
The densely welded parts of the Prow Pass tuff, Bullfrog tuff, and Tram tuff are likely to have 
mean permeabilities that are less than the mean air permeabilities of the Tiva Canyon 
(k = 4.7 x 1012 m2) or Topopah Spring (k = 0.75 x 1012 m2) tuffs estimated from 
air-permeability tests. This likelihood is because greater lithostatic stresses at depth tend to close 
fractures and successive hydrothermal events have caused increasing degrees of alteration with 
depth (Broxton et al. 1987 [DIRS 102004]). Figure 7-3 shows the geometric-mean 
permeabilities from the single-hole air-permeability tests for the Tiva Canyon and Topopah 
Spring tuffs and the Geometric-mean single-hole water permeabilities calculated for the Calico 
Hills Formation and the Prow Pass, Bullfrog, Tram, and Lithic Ridge tuffs as a function of 
relative stratigraphic position. The single-hole permeabilities show the expected trends with 
depth. Conversely, the trends in the cross-hole permeability data from the C-wells (see 
Section 7.2.2.3.2 and Section 7.2.2.6, Figure 7-4) are exactly opposite the trends one would 
expect to see based on geologic reasoning; these trends do, however, reflect the proximity of 
each hydrogeologic unit to the Midway Valley fault, which intersects the C-wells in the upper 
part of the Tram tuff (Geldon et al. 1998 [DIRS 129721], Figure 3). Thus, it appears that 
permeability trends with depth at the C-wells are controlled by local conditions and do not reflect 
general trends in permeability established by the single-hole tests and expected from geologic 
reasoning. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-17 November 2004 
Increasing stratigraphic depth 
Logarithm of permeability (in meters-squared) 
-16 
-15 
-14 
-13 
-12 
-11 
-10 
Tiva Canyon Tuff 
Topopah Spring Tuff 
Calico Hills Tuff 
Prow Pass Tuff 
Bullfrog Tuff 
Tram Tuff 
Lithic Ridge Tuff 
Source DTNs: GS960908312232.012 [DIRS 114124] (Tiva and Topopah units); DTN: SNT05082597001.003 
([DIRS 129714]) (All other units). Used for corroboration only. 
Figure 7-3. Comparison of UZ and SZ Permeabilities 
Overall, an upper limit of 60 x 1012 m2 in the most critical alluvial formations is expected, and 
this value is used in the PEST model calibrations of the SZ SS flow model. 
7.2.2.2 Implications of Permeability Data on Specific Discharge Estimates 
The depth-dependent trends in mean hydrogeologic-unit permeabilities indicated by the 
combined air-permeability data from the unsaturated zone and the water-permeability data from 
the SZ (Section 7.2.2.3.2 and Section 7.2.2.6, Figure 7-4) are consistent with the trends expected 
as higher lithostatic stresses and more intense hydrothermal alterations close fractures at 
increasing depths. Conversely, permeabilities measured from cross-hole tests at the C-wells 
(Section 7.2.2.3.2 and Section 7.2.2.6, Figure 7-4) indicate trends that reflect proximity to the 
Midway Valley fault. Recent studies at the Apache Leap site in Arizona have indicated that 
single-hole and cross-hole tests should yield the same mean permeabilities once heterogeneity 
and departures from idealized flow geometries are properly taken into account. Therefore, 
except for the Calico Hills Formation, the single-hole permeabilities reflect the true 
permeabilities of the hydrogeologic units in unfaulted areas and can be used to represent the 
hydrogeologic-unit permeabilities in specific-discharge calculations or in numerical models, 
provided the effects of faults are also accounted for in some manner. The geometric-mean 
permeability estimated for the Calico Hills Formation was probably unduly biased toward that of 
faulted locations by data from boreholes UE-25 b#1 and UE-25 J-13. In unfaulted areas, the 
Calico Hills Formation permeability is probably several orders of magnitude less than the 
geometric-mean permeability calculated from the single-hole tests. The similarity of 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-18 November 2004 
geometric-mean permeability values from cross-hole air-permeability testing in the Ghost Dance 
fault (k = 14.6 x 1012 m2) and the maximum permeabilities from cross-hole testing at the 
C-wells (54.0 x 1012 m2) indicate that values of 10.0 x 1012 to 50.0 x 1012 m2 may be 
appropriate as fault zone properties in numerical models so long as the modeled width reflects 
the true width of the fault; otherwise, the permeabilities in the model should be adjusted to 
preserve the overall transmissivity of the faults. The maximum permeability values that have 
been calculated for faulted locations at the C-wells and alcoves in the Ghost Dance fault provide 
upper bounds on the permeability values that would be representative of the tuffs at unfaulted 
locations (k = 50.0 x 1012 m2). The expected values of the tuffs are provided by the geometric 
means calculated from the single-hole tests and are one to several orders of magnitude less than 
this likely upper bound. 
7.2.2.3 Permeability Data from the Yucca Mountain Area 
Permeability data from single-hole and cross-hole tests were collected in the Yucca Mountain 
area from the early 1980s to the present day Nye County wells. The test results published up to 
1997 were compiled in DTN: SNT05082597001.003 [DIRS 129714] (for reference only). 
A statistical analysis of this data set is presented in this section. In addition to permeability data 
previously available during the development of the SZ site-scale model, additional permeability 
measurements are now available from the ATC. These data are reported below as well. 
7.2.2.3.1 Single-Hole Tests 
The statistical analysis that follows required that the test results be grouped. This grouping was 
done by first compiling the permeability estimates for individual hydrogeologic units, where 
possible, and by considering progressively more general groupings for those cases in which the 
test interval spanned several hydrogeologic units. For instance, in cases in which the test interval 
was in the Prow Pass tuff, with or without some portion of the adjacent ash fall, the test results 
were grouped with other permeability estimates for the Prow Pass tuff. If other units within the 
middle volcanic aquifer (MVA), as defined by Luckey et al. (1996 [DIRS 100465], Figure 7), 
were also present in the test interval along with the Prow Pass tuff, the test results were 
considered to represent the MVA. If hydrogeologic units other than those in the MVA were 
present in the test interval along with the Prow Pass tuff, the permeability estimate for the test 
was grouped with the most general category, which is mixed tuffs. The mixed-tuff category 
includes data for all tests that would not fit into a more restrictive category. All tuffs older than 
the Lithic Ridge tuff are listed as Pre-Lithic Ridge tuffs (older tuffs). The other categories 
were named for the hydrogeologic unit to which they pertain and are believed to be 
self-explanatory. 
There were several instances in which several kinds of hydraulic tests (injection, drawdown, or 
recovery) were conducted in the same depth interval in the same borehole. The results of these 
tests could have been treated in several different ways. For example, (1) the data for a particular 
depth interval could have been averaged and only the single average value considered in the 
statistical summary, in which case the statistical uncertainty could be interpreted as reflecting 
only the effects of spatial variability, or (2) all of the permeabilities that resulted from testing of 
the interval could have been used to calculate the summary statistics, which was done in this 
report. By considering multiple measurements from the same test interval, this statistical 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-19 November 2004 
analysis attempts to reflect the effects of measurement uncertainty as well as the effects of spatial 
variability. 
The base-10 logarithms of the permeabilities were calculated (Section 6-8) and a statistical 
analysis was performed on the log-transformed values for each category (CRWMS M&O 
[DIRS 139582]). The antilogarithms of the statistical parameters for each category were 
calculated and are listed in Table 6-24. The analysis indicates that the deepest tuffs, which are 
the Pre-Lithic Ridge tuffs (Pre-Tlr), and the mixed tuff group has the lowest permeabilities, and 
the Topopah Spring tuff and Prow Pass tuff have the largest permeabilities. Where they could be 
calculated, the 95 percent confidence limits indicate that the mean permeability values are 
constrained within relatively narrow limits, except for the Pre-Lithic Ridge tuffs. 
The results also indicate that the Calico Hills Formation, which is a zeolitized tuff that functions 
as the upper volcanic confining unit (Luckey et al. 1996 [DIRS 100465], Figure 7), has a higher 
permeability than the Bullfrog tuff and the carbonate aquifer. This paradoxical result may reflect 
the fact that, because it is unsaturated in the western half of Yucca Mountain, the Calico Hills 
Formation could be hydraulically tested only in the highly faulted eastern half of Yucca 
Mountain, whereas the other units were also tested in less intensely faulted areas to the west. 
Single-well hydraulic testing of the saturated alluvium in well NC-EWDP-19D1 of the ATC was 
conducted between July 2000 and November 2000. During this testing, a single-well test of the 
alluvium aquifer to a depth of 812 feet (247.5 m) below land surface was initiated to determine 
the transmissivity and hydraulic conductivity of the entire alluvium system at the NC-EWDP- 
19D1 location. In addition, each of the four intervals in the alluvium in NC-EWDP-19D1 were 
isolated and hydraulically tested to obtain transmissivity and associated hydraulic conductivity. 
This interval-testing program was initiated in an effort to evaluate heterogeneity in hydraulic 
properties over the thickness of the alluvium at the NC-EWDP-19D1 location to help determine 
the conceptual model of flow in the saturated alluvium south of Yucca Mountain. The results of 
this testing are presented in Table 7-4. 
7.2.2.3.2 Cross-Hole Tests 
Permeability data from cross-hole tests were compiled, grouped, and analyzed in a manner 
similar to the permeability data for the single-hole tests (see Table 6-24). The cross-hole data 
originate from tests conducted at the C-wells complex. Whereas the permeabilities of the Calico 
Hills formation are similar for both the single- and cross-hole tests, the permeabilities of the 
Prow Pass tuff, Bullfrog tuff, Tram tuff of the Crater Flat group, and the MVA calculated from 
the cross-hole tests are one to several orders of magnitude greater than the mean permeabilities 
calculated from the single-hole tests. The differences in the mean permeability values between 
the single- and cross-hole tests generally have been attributed to the larger volume of rock 
affected by the cross-hole tests (Geldon et al. 1997 [DIRS 100397]), which allows a larger 
number of possible flow paths, including relatively rare, high-transmissivity flow paths, to be 
sampled during the test. However, some of the increase in permeability attributed to the effects 
of scale may also be due to the presence of a breccia zone associated with the Midway Valley 
fault in the Bullfrog tuff and Tram tuff at boreholes UE-25 c#2 and UE-25 c#3 (Geldon et al. 
1997 [DIRS 100397], Figure 3). Thus, some of the difference in the mean permeabilities 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-20 November 2004 
calculated for the single-hole and cross-hole tests may be due both to local conditions in the 
vicinity of the C-wells and to scale. 
Table 7-4. Transmissivities, Hydraulic Conductivities, and Permeabilities Determined in the Single-Well 
Hydraulic Tests Conducted in the Alluvium in NC-EWDP-19D1 Between July and 
November 2000 
Test Interval 
(ft below 
land 
surface)a 
Apparent 
Transmissivity 
of Intervalb 
(ft2/day) 
Apparent 
Transmissivity of 
Total Saturated 
Alluviumc 
(ft2/day) 
Hydraulic 
Conductivity 
Based on Sand 
Pack Thicknessd 
(ft/day) 
Hydraulic 
Conductivity 
Based on 
Distance from 
Water Tablee 
(ft/day) 
Permeability 
(m2) 
Combined-Interval Test 
Four 
combined 
intervals 
223 223 0.5 0.5 2.7 x 10-13 
Isolated-Interval Tests 
#1: 412437 66 335 2.0 0.75 2.71 x 10-13 
#2: 490519 7.5 N/A 0.23 0.04 1.44 x 10-14 
#3: 568691 223 291 1.74 0.65 2.35 x 10-13 
#4. 717795 300 300 3.57 0.67 2.42 x 10-13 
Source: BSC 2004 [DIRS 170010], Appendix F. 
a Depths correspond to upper and lower extent of sand packs. 
b Transmissivity, as obtained directly from applying the Neuman (1975 [DIRS 150321]) solution to the drawdown in 
the interval tested, of the saturated alluvium from the water table to the bottom of the screen being tested. Ignoring 
screen #2, which is affected by a local clay layer, these transmissivities increase monotonically as the depth of the 
screen being tested increases. 
c Transmissivity calculated from the screens #1, #3, and #4 interval tests for the entire saturated alluvium thickness 
tested by multiplying the transmissivity value in the second column, which is for the interval from the water table to 
the bottom of the screen being tested, by the ratio of 446 feet (the total saturated alluvium thickness tested) over 
the depth from the water table to the bottom of the screen being tested. Thus, for screen #1, 66 x (446/88) = 334.5 
 335 ft2/day. For screen #3, 223 x (446/342) = 290.8  291 ft2/day. No corrections are needed for the combinedinterval 
test or for the screen #4 test. 
d Assumes that interval thickness is the thickness of the interval sand pack. 
e Assumes that interval thickness is the distance from the water table to the bottom of the screened interval being 
pumped. 
A cross-hole hydraulic test was also conducted at the ATC in January 2002. During this test, 
borehole NC-EWDP-19D1 was pumped in the open-alluvium section, while IM1 and IM2 were 
used as monitoring wells. IM1 was packed off, isolating each of four intervals in the alluvium 
section, while IM2 had only one packer inflated, isolating the alluvium section from the intervals 
below it. The analyses of the drawdown data from IM2 resulted in an estimated transmissivity 
value of 3,300 ft2/day (0.00355 m2/s). The transmissivity estimate is approximately an 
order-of-magnitude higher than the 300-ft2/day (0.000322-m2/s) value obtained from single-hole 
testing in 19D1. The differences between cross-hole and single-well tests are likely the result of 
large head losses in the single-hole testing due to the well efficiency of 19D1. The tested 
interval in IM2, from the water table to the bottom of screen #4, is 438 feet (133.5 m). 
Therefore, the intrinsic permeability measured in this test is 2.7 x 10-12 m2. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-21 November 2004 
7.2.2.4 Permeability Data from the Nevada Test Site 
Data from reports pertaining to the NTS were examined to help constrain permeability estimates 
for hydrogeologic units that were either not tested or that underwent minimal testing at 
Yucca Mountain. These permeability data, as well as more qualitative observations concerning 
the permeability of some of the hydrogeologic units in the site-scale model area, are summarized 
in the following sections. Additionally, these reports, including Blankennagel and Weir 
(1973 [DIRS 101233]), Winograd and Thordarson (1975 [DIRS 101167]), and Laczniak et al. 
(1996 [DIRS 103012]), describe the hydrogeologic controls on groundwater movement at the 
NTS, thereby providing a regional perspective for groundwater flow at Yucca Mountain. 
Assessments of permeability data from the NTS for the lower carbonate aquifer, the valley fill 
aquifer, the welded tuff aquifer, and the lava flow aquifer are presented below. 
7.2.2.4.1 Lower Carbonate Aquifer (Unit 4) 
The results of hydraulic tests in the lower carbonate aquifer were reported for eight boreholes by 
Winograd and Thordarson (1975 [DIRS 101167], Table 3). For two of the boreholes, only 
transmissivity estimates based on specific capacity were made. At boreholes for which 
permeability estimates based on drawdown curves were also available, the estimates based on 
specific capacity were much lower than the estimates based on the drawdown curves. At 
five boreholes where both drawdown and recovery tests were conducted, the permeabilities 
estimated from recovery tests were several times higher than those estimated from drawdown 
tests. Both the drawdown and recovery data exhibited complex responses to pumping that were 
attributed to test conditions as well as to aquifer properties. These responses were manifested on 
log-linear plots of time versus drawdown as straight-line segments with distinct breaks in slope. 
Because they were unable to explain the differences in the results from the drawdown and 
recovery tests, Winograd and Thordarson (1975 [DIRS 101167], p. C25) advised against the use 
of the transmissivities estimated from the recovery tests. The transmissivities estimated from 
drawdown tests in the lower carbonate aquifer are listed for six boreholes in Table 7-5 along with 
thicknesses of the test intervals and the calculated permeabilities. The permeabilities in m2 were 
calculated from the hydraulic conductivity values using a viscosity of 0.001 Pascal seconds, a 
density of 1,000 kg/m3, and a gravitation acceleration of 9.81 m/s2. These viscosity and density 
values are appropriate for test temperatures of about 25C. The actual test temperatures were not 
reported by Winograd and Thordarson (1975 [DIRS 101167]) but may have been substantially 
higher (greater than 50C) than the temperatures assumed in this calculation, in which case the 
calculated permeabilities may overestimate the true permeabilities measured by the tests by a 
factor of 2 to 3. A statistical analysis of the base-10 logarithms of the permeabilities listed in 
Table 7-4 resulted in an estimated mean permeability for the carbonate aquifer of 6.0 x 1013 m2. 
The 95 percent lower and upper confidence limits for the mean permeability were 1.39 x 10-13 m2 
and 2.58 x 1012 m2, respectively. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-22 November 2004 
Table 7-5. Permeabilities Calculated for the Lower Carbonate Aquifer 
Well 
Thickness 
(ft) 
Transmissivitya 
(gpd/ft)b 
Hydraulic 
Conductivity 
(gpd/ft2) 
Permeability 
(m2) 
67-73 281 20,000 71.2 3.44 x 1012 
67-68 996 39,000 39.2 1.89 x 1012 
66-75 753 11,000 14.6 7.05 x 1013 
88-66 872 1,300 1.49 7.19 x 1014 
75-73 750 3,800 5.07 2.45 x 1013 
84-68 205 2,400 11.7 5.65 x 1013 
Source: Winograd and Thordarson 1975 (DIRS 101167), Table 3. 
NOTE: Statistics for the logarithm of permeability (log k) are 
Mean = 12.224 
Standard deviation = 0.605 
Median = 12.999 
Lower 95 percent confidence level for mean = 12.858 
Upper 95 percent confidence level for mean = 11.5887. 
a These transmissivities were estimated by Winograd and Thordarson (1975 [DIRS 101167], Table 3) from 
drawdown curves. 
b gpd is gallons per day. 
In addition to providing quantitative estimates of the permeability, Winograd and Thordarson 
(1975 [DIRS 101167]) made several qualitative observations regarding the distribution of 
permeability within the carbonate aquifers. 
The permeability data for the carbonate aquifer showed no systematic decrease either with depth 
beneath the top of the aquifer or beneath the land surface (Winograd and Thordarson (1975 
[DIRS 101167], p. C20). The inference that groundwater may circulate freely within the entire 
thickness of the lower carbonate aquifer is not negated by chemical data, which indicate no 
significant increase in the dissolved-solids content to depths of several thousand feet (Winograd 
and Thordarson (1975 [DIRS 101167], p. C103). 
No major caverns were detected during drilling in the lower carbonate aquifer, despite the fact 
that approximately 16,000 feet (4877 m) of the lower carbonate aquifer was penetrated in 26 
holes drilled in 10 widely separated areas, including over 5,000 feet (1524 m) at 13 holes beneath 
the Tertiary/pre-Tertiary unconformity, where caverns might be expected to exist (Winograd and 
Thordarson (1975 [DIRS 101167], p. C19). Drill-stem tests in three holes in the Rock Valley 
and Yucca Flat indicated negligible to moderate permeability immediately below the 
unconformity (Winograd and Thordarson (1975 [DIRS 101167], p. C20). Outcrop evidence 
indicates that klippen, which are the upper plates of low-angle thrust faults and gravity slump 
faults, have a higher intensity of fracturing and brecciation than rock below the fault planes and 
may have above-average porosity and permeability (pp. C19 to C20). Specific capacity data for 
five wells penetrating the upper plates of low-angle faults in southern Yucca Flat and the 
northwestern Amargosa Desert indicated relatively high transmissibilities for these plates 
(Winograd and Thordarson (1975 [DIRS 101167] p. C28). 
The presence of hydraulic barriers within the lower carbonate aquifer is indicated in the 
hydraulic response in two-thirds of the wells pumped, indicating that zones of above-average 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-23 November 2004 
transmissivity may often not be connected to each other (Winograd and Thordarson (1975 
[DIRS 101167], p. C116). However, this observation needs to be reconciled with hydraulic and 
chemical evidence supporting the existence of a mega channel extending over 40 miles 
(64 km) between southern Frenchman Flat and the discharge area at Ash Meadows (Winograd 
and Pearson 1976 [DIRS 108882]). 
7.2.2.4.2 Valley Fill Aquifer (Unit 20) 
The valley fill aquifer, as defined by Winograd and Thordarson (1975 [DIRS 101167], 
Table 1, p. C37) is composed of alluvial fan, fluvial, fanglomerate, lakebed, and mudflow 
deposits in depressions created by post-Pliocene block faulting. Thus defined, the valley fill 
aquifer of Winograd and Thordarson (1975 [DIRS 101167]) probably includes the valley fill 
aquifer (Unit 20), the valley-fill confining unit (Unit 19), and the undifferentiated valley fill 
(Unit 8) defined for the present study. 
Transmissivity estimates for the valley-fill aquifer were made at six boreholes in Emigrant 
Valley, Yucca Flat, and Frenchmen Flat (Winograd and Thordarson 1975 [DIRS 101167], 
Table 3). For two of the boreholes, only transmissivity estimates based on specific capacity data 
were available. However, these estimates are considered unreliable because of the lack of 
agreement with transmissivity estimates based on drawdown or recovery curves at boreholes in 
which both types of estimates were made. The transmissivity estimates made from drawdown 
and recovery curves were consistent with each other at wells where both types of tests were 
conducted, in which case the transmissivity values from the drawdown and recovery curves were 
averaged to produce the transmissivity estimates listed in Table 7-6. Values used for the 
viscosity, density, and gravity terms in the expression for permeability are the same as those used 
for the lower carbonate aquifer. Based on a statistical analysis of the logarithm of the 
permeabilities listed in Table 7-5, the mean permeability of the valley fill is 1.57 x 1012 m2, and 
the 95 percent lower and upper confidence limits for the mean permeability are 1.61 x 1013 and 
1.54 x 1011 m2, respectively. The relatively high mean permeability calculated for the valley fill 
is probably more reflective of the permeability of the valley-fill aquifer (Unit 20) and, possibly, 
the undifferentiated valley fill (Unit 8) of this study than of the valley-fill confining unit 
(Unit 19). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-24 November 2004 
Table 7-6. Permeability Estimates for the Valley Fill Aquifer 
Well 
Thickness 
(ft) 
Transmissivity 
(gpd/ft) 
Hydraulic Conductivity 
(gpd/ft2) 
Permeability 
(m2) 
74-70 b 511 2,200 a 4.31 2.08 x 1013 
74-70 a 217 9,350 b 43.1 2.08 x 1012 
83-68 264 12,700 b 48.1 2.32 x 1012 
91-74 264 33,500 c 126.9 6.12 x 1012 
Source: Winograd and Thordarson 1975 (DIRS 101167), Table 3. 
NOTE: Permeability estimates based on transmissivity data from Winograd and Thordarson (1975 
[DIRS 101167], Table 3). 
Statistics for the logarithm of permeability (log k) are 
Mean = 11.803 
Standard deviation = 0.623 
Median = 11.658 
Lower 95 percent confidence level for mean = 12.794 
Upper 95 percent confidence level for mean = 10.812. 
aAverage is the arithmetic sum of the results of one drawdown and two recovery tests. 
bAverage is the arithmetic sum of the results of one drawdown and one recovery test. 
c Representative Value is the result of one recoverytest. 
gpd=gallons per day 
In addition to providing the quantitative estimates of the permeability of the valley fill 
summarized in this section, Winograd and Thordarson 1975 [DIRS 101167]) also made 
numerous observations regarding the permeability of the valley fill at particular locations in the 
area of the NTS. Of special interest to this report are those observations made for the valley fill 
in the Amargosa Desert. Winograd and Thordarson (1975 [DIRS 101167], pp. C84 to C85) 
noted that hydraulic head contours south of Amargosa Valley (formerly called Lathrop Wells) 
probably reflect the effects of upward leakage from the lower carbonate aquifer into poorly 
permeable valley fill along the Gravity fault and associated faults and of the drainage of this 
water to more permeable sediments farther west. Immediately west of the Gravity fault, gravity 
data indicate that downward displacement of the pre-Tertiary rocks west of the fault is 500 to 
1,500 ft (152.4 to 457.2 m) at a location one mile east of Amargosa Valley and 1,200 to 2,200 ft 
(365.8 to 670.6 m) at a point one mile southeast of the inferred intersection of the Specter Range 
Thrust fault and the Gravity fault. The low permeability of the valley fill immediately west of 
the Gravity fault was indicated by drillers logs, which showed that the valley fill in this area was 
mainly clay, and also by analogy with the lakebed sediments southwest of the spring line at Ash 
Meadows, where groundwater discharging from the lower carbonate aquifer into the sediments 
across the Gravity fault is forced to the land surface by the low permeability of the sediments. 
Winograd and Thordarson (1975 [DIRS 101167], p. C85) argued that the discharge across the 
Gravity fault near Amargosa Valley was probably small because only the lower-most part of the 
lower carbonate aquifer is present in the area and the lower clastic aquitard, which underlies the 
carbonate aquifer at shallow depths, would probably not transmit much water. 
7.2.2.4.3 Welded Tuff Aquifer (Unit 16) 
The welded tuff aquifer corresponds to the upper volcanic aquifer (Unit 16) of Table 6-3. 
Results of hydraulic tests conducted in the welded tuff aquifer were reported by Winograd and 
Thordarson (1975 [DIRS 101167], Table 3) for four wells, but only two wells, both in Jackass 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-25 November 2004 
Flats, had transmissivity estimates based on drawdown curves. Well 74-57 tested the Topopah 
Spring tuff and well 74-61 tested both the Topopah Spring tuff and the Basalt of Kiwi Mesa. 
Permeabilities calculated from the drawdown curves at these wells are listed in Table 7-7. The 
geometric mean permeability, based on the estimated permeabilities in Table 7-7, is 
5.3 x 10-12 m2. 
Table 7-7. Permeability Estimates for the Welded Tuff Aquifer 
Well 
Thickness 
(ft) 
Transmissivity 
(gpd/ft) 
Hydraulic Conductivity 
(gpd/ft2) 
Permeability 
(m2) 
74-61 290 28,000 96.6 4.7 x 1012 
74-57 547 68,000 124.3 6.0 x 1012 
Source: Winograd and Thordarson 1975 (DIRS 101167), Table 3. 
NOTE: Permeability estimates based on transmissivities determined from drawdown curves (Winograd and 
Thordarson 1975 [DIRS 101167], Table 3). Statistics: The geometric mean permeability is 5.3 x 10 
12 m2. 
gpd = gallons per day. 
7.2.2.4.4 Lava Flow Aquifer (Unit 17) 
Rhyolitic lavas and welded and nonwelded tuffs fill the Silent Canyon caldera complex, which 
now lies buried beneath Pahute Mesa by younger tuffs, erupted from the Timber Mountain 
caldera complex to the south (Blankennagel and Weir 1973 [DIRS 101233], p. 6; Laczniak et al. 
1996 [DIRS 103012], p. 36). The permeabilities of the lava flows beneath Pahute Mesa are 
assumed to be an appropriate analogue for the Lava Flows (Unit 17) near Yucca Mountain. 
A qualitative comparison of the water-producing attributes of the lavas and tuffs based on the 
concept of specific capacity (in gal/min/ft of drawdown) indicated that despite considerable 
overlap in their water-yield potential, the lavas generally were the most transmissive rocks 
tested, followed by the welded tuffs and, finally, the zeolitized nonwelded tuffs (Blankennagel 
and Weir 1973 [DIRS 101233], Figure 4). Pumping tests were conducted in 16 boreholes at 
Pahute Mesa, including 14 in which the major water production came from the rhyolitic lava 
flows (Blankennagel and Weir 1973 [DIRS 101233], Table 3). The borehole names, uncased 
saturated thickness, measured transmissivities, and calculated hydraulic conductivities and 
permeabilities associated with these 14 tests are given in Table 7-8. The mean permeability of 
the rhyolitic lava is estimated to be 2.67 x 1013 m2, with 95 percent lower and upper confidence 
limits of 9.18 x 1014 m2 and 7.76 x 1013 m2, respectively. However, these estimates should be 
viewed as approximate lower bounds because other, less permeable rocks (welded and 
nonwelded tuffs) are present in the test interval, and these less permeable rocks would cause the 
transmissivity to be lower than the transmissivity that would be expected if only lava had been 
present. Resistivity logs indicated that nonwelded tuffs could constitute as much as 73 percent of 
the upper 2000 ft of saturated rock at the boreholes listed in (Blankennagel and Weir 1973 
[DIRS 101233], Table 2). Because most of the water pumped from the lava enters the wells 
from zones that constitute only 3 to 10 percent of the total saturated thickness (Blankennagel and 
Weir 1973 [DIRS 101233], p. 11), permeabilities in the lava may be locally much higher than the 
calculated mean value. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-26 November 2004 
Table 7-8. Permeabilities of the Lava Flow Aquifer 
Well 
Uncased, Saturated 
Thickness (ft)a 
Transmissivity 
(gpd/ft)b 
Hydraulic Conductivity 
(gpd/ft2) 
Permeability 
(m2) 
UE-18r 3,375 23,000 6.82 3.28 x 1013 
TW-8 4,422 185,000 41.8 2.01 x 1012 
UE19b-1 2,310 56,000 24.2 1.17 x 1012 
UE19c 2,099 12,000 5.72 2.75 x 1013 
UE-19d 5,129 20,000 3.90 1.88 x 1013 
UE-19fs 2,214 11,000 4.97 2.39 x 1013 
UE-19gs 1,858 30,000 16.1 7.77 x 1013 
UE-19h 1,383 140,000 101.0 4.87 x 1012 
UE-19I 5,104 1,400 0.274 1.32 x 1014 
U-20a-2 2,434 18,000 7.40 3.56 x 1013 
UE-20d 2,047 44,000 21.5 1.03 x 1012 
UE-20e-1 4,573 8,300 1.82 8.73 x 1014 
UE-20f 9,230 1,000 0.108 5.21 x 1015 
UE-20h 4,701 11,000 2.34 1.13 x 1013 
Source: Blankennagel and Weir 1973 [DIRS 101233], Table 3. 
NOTE: Statistics for the logarithm of permeability (log k) are: 
Mean = 12.574 
Standard deviation = 0.803 
Median = 12.521 
Lower 95 percent confidence level for mean = 13.037 
Upper 95 percent confidence level for mean = 12.110 
a Uncased, saturated thickness was calculated as the depth to water or depth of casing, whichever was greater, 
minus the depth of the well. The depth to water was used for TW-8, where the casing was perforated. 
b gpd is gallons per day 
7.2.2.5 Inferences About Permeability from Regional Observations 
In addition to the permeability values from the NTS summarized in the previous section, 
Winograd and Thordarson (1975 [DIRS 101167]) made numerous qualitative evaluations of the 
relative magnitude of permeability for different hydrogeologic units. These evaluations were 
based on examination of core for fractures and mineral infilling, the geologic setting and the 
magnitude of discharge of springs in the region, and the correspondence between changes in 
hydraulic gradients and the underlying hydrogeologic unit. Sections 7.2.2.5.1 through 7.2.2.5.3 
focus on qualitative assessments of hydrogeologic units that have little actual test data and for 
which the qualitative evaluations, thus, assume relatively more importance. 
7.2.2.5.1 Lower Clastic Aquitard (Unit 3) 
The Lower Clastic Aquitard of Winograd and Thordarson (1975 [DIRS 101167], Table 1) 
corresponds to the lower clastic confining unit (Unit) of Table 6-3. According to Winograd and 
Thordarson (1975 [DIRS 101167], p. C43), the large-scale transmissivity of the lower clastic 
aquitard is probably controlled by its interstitial permeability, which, based on the hydraulic 
conductivity of 18 cores (Winograd and Thordarson 1975 [DIRS 101167], Table 4), ranges from 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-27 November 2004 
3.4 x 1020 m2 to 4.8 x 1018 m2 and has a median value of 9.7 x 1020 m2. Although the lower 
clastic aquitard is highly fractured, Winograd and Thordarson (1975 [DIRS 101167], p. C43) 
argued that fractures probably do not augment the interstitial permeability of the unit on a 
regional scale to the same degree as in the lower carbonate aquifer for the following reasons: 
 The argillaceous formations within the unit have a tendency to deform plastically, that 
is, by folding, rather than by fracturing. Thus, fracture continuity across the lower 
clastic aquitard is disrupted by the argillaceous layers. 
 Micaceous partings and argillaceous laminae tend to seal the fractures in the brittle 
quartzite parts of the unit, reducing or eliminating the ability of the fractures to transmit 
water. 
 The clastic rocks that constitute the unit have a low solubility; therefore, solution 
channels, which can further enhance permeability along fractures in carbonate rocks, are 
not likely to be present in this unit. 
The low permeability of the lower clastic aquitard compared to the carbonate rocks also was 
indicated by the observation that, in the Spring Mountains, the total discharge issuing from the 
lower clastic aquitard is only a small fraction of the total discharge of the springs in the lower 
carbonate aquifer (Winograd and Thordarson 1975 [DIRS 101167], pp. C42 to C43, C53). The 
comparatively low permeability of the Clastic Aquitard also is indicated by a head drop across 
the lower clastic aquitard of 2000 ft (609.6 m) over a distance of less than 8 miles (12.8 km) (an 
apparent hydraulic gradient of 250 ft/mile (47.6 m/km)) in the hills northeast of Yucca Flat 
(Winograd and Thordarson 1975 [DIRS 101167], Plate 1). In contrast, the hydraulic gradient in 
the carbonate aquifer ranges from 5.9 ft/mile (1.12 m/km) or less along the axis of the 
potentiometric trough in Yucca Flat to 20 ft/mile (3.8 m/km) along the flanks of the trough 
(Winograd and Thordarson 1975 [DIRS 101167], p. C71). 
7.2.2.5.2 Upper Clastic Aquitard (Unit 5) 
The upper clastic aquitard is equivalent to the upper clastic confining unit (Unit 5) of Table 6-18. 
The upper clastic aquitard corresponds to the Eleana formation, which consists of argillite, 
quartzite, conglomerate, and limestone (Winograd and Thordarson 1975 [DIRS 101167], 
Table 1). The upper two-thirds of the unit consists mainly of argillite, whereas the lower 
one-third of the unit is principally quartzite (Winograd and Thordarson 1975 [DIRS 101167], 
p. C118). Winograd and Thordarson (1975 [DIRS 101167], p. C43) argued that fractures were 
unlikely to remain open in the rock at depth because of the plastic deformation behavior of the 
rock, which is evidenced by tight folds, and the fact that the formation serves as a glide plane for 
several thrust faults at the NTS. No core-scale permeability measurements exist, but based on 
analogy with the lower clastic aquitard, its interstitial permeability probably is less than 
1 x 10-4 gpd/ft2 (4.8 x 10-18 m2) (Winograd and Thordarson 1975 [DIRS 101167], p. C43). In the 
hills northwest of Yucca Flat, an approximately 2,000-ft (607.6-m) drop in hydraulic head in the 
pre-Tertiary rocks over a distance of less than 10 miles (an apparent hydraulic gradient of 
200 ft/mile (38 m/km)) suggests a comparatively low regional permeability for the upper clastic 
aquitard. However, because land-surface elevation changes abruptly over this same distance and 
because water table elevations often mimic ground-surface elevations, it is not possible to isolate 
the effects of permeability from the effects of topography on the head gradient in this area. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-28 November 2004 
7.2.2.5.3 Faults 
A summary of the possible effects of faults on groundwater movement in the Death Valley 
region is presented by Faunt (1997 [DIRS 100146]). The transmissivity of faults was described 
by Faunt (1997 [DIRS 100146], p. 30) to be a function of many factors: 
 The orientation of the fault relative to the minimum horizontal stress in the region. 
 The amount and type of fill material in the fault. 
 The relative transmissivities of hydrogeologic units juxtaposed by offset across the fault. 
 The solubility and deformation behavior of the rock adjacent to the fault. 
 Recent seismic history. 
7.2.2.5.3.1 Orientation of Faults Relative to the Minimum Horizontal Stress in the Region 
In the vicinity of Yucca Mountain, the mean azimuth of the minimum horizontal stress is 
306  11 degrees (Faunt 1997 [DIRS 100146], Table 4-4), so that faults with traces oriented 
north-northeast are expected to be more open and permeable than faults with traces oriented in 
directions that place them in either a shear or a compressive state. Faults oriented northwest, or 
perpendicular to the maximum horizontal stress direction, would be expected to be least 
transmissive, all other factors being equal. One example cited by Faunt (1997 [DIRS 100146], 
pp. 34 to 35) to illustrate the northeast-southwest trending structures that may have relatively 
high transmissivity is the megachannel formed in the Spotted Range-Mine Mountain shear 
zone between Frenchman Flat and Ash Meadows. The presence of a highly transmissive zone in 
the carbonate aquifer was indicated by a potentiometric trough in this area and relatively young 
carbon-14 ages of groundwater discharging from springs at the distal end of the trough 
(Winograd and Pearson 1976 [DIRS 108882]). 
7.2.2.5.3.2 Amount and Type of Infilling Material in the Fault 
Fine-grained gouge or clayey infilling material can cause faults to become poorly transmissive, 
even if their orientation relative to the stress field indicates they have the potential to be highly 
transmissive. The effects of deformation behavior, solubility, and infilling material in the clastic 
aquitards and carbonate aquifer were discussed in Section 7.2.2.5.1 and Section 7.2.2.5.2. 
Solution channels along faults in the carbonate rock have the potential to further enhance the 
transmissivity of faults in this unit. 
7.2.2.5.3.3 Relative Transmissivities of Hydrogeologic Units Juxtaposed by Offset Across 
the Fault 
Where faults juxtapose hydrogeologic units with contrasting permeabilities, the hydrologic 
effects caused by juxtaposition may be difficult to isolate from the effects of the fault properties 
themselves. As indicated in Faunt (1997 [DIRS 100146], Figure 16), an increase in the local 
head gradient compared to the regional gradient can occur across a fault if: 
 The fault is closed, thereby blocking flow. 
 The fault is open, thereby redirecting flow. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-29 November 2004 
 The permeability of the material downgradient of the fault is low compared to the 
upgradient material, so that flow across the fault is blocked. 
 The permeability of the material downgradient of the fault is high compared to the 
upgradient material, so that flow can drain away from the fault faster than it can be 
delivered by the upgradient material. 
Evidence that springs in Ash Meadows are caused by the juxtaposition of poorly permeable 
sediments and rocks downgradient of the carbonate aquifer across the Gravity fault was 
presented in Winograd and Thordarson (1975 [DIRS 101167], p. C82). Hydraulic data in 
southern Indian Springs Valley were interpreted by Winograd and Thordarson 
(1975 [DIRS 101167], p. C67 to C68) to indicate the presence of two hydraulic barriers related 
to the Las Vegas shear zone: (1) a northern barrier caused by the juxtaposition of the lower 
clastic aquitard and lower carbonate aquifer; and (2) a southern barrier, which was attributed to 
the presence of gouge along a major fault zone. 
7.2.2.5.3.4 Recent Seismic History 
The seismic history of the faults may indicate which faults have undergone recent movement. 
Recent movement on a fault may serve to break calcite or silica cement or other material that 
may have closed the fault. A map showing which faults or fault segments near Yucca Mountain 
have undergone recent movement was developed by Simonds et al. (1995 [DIRS 101929]). Of 
the faults that have been mapped near the repository area, only the Solitario Canyon fault and 
short segments of the Bow Ridge fault near Exile Hill show evidence of late Quaternary (or more 
recent) movement. 
7.2.2.6 Comparing Permeability Data to Calibrated Permeability Values 
To check if the permeabilities estimated by PEST61564]) during the calibration of the SZ 
site-scale model are reasonable, the logarithms of permeabilities estimated during calibration of 
the model are compared to the mean logarithms of permeability estimated from pump-test data 
from Yucca Mountain in Figure 7-4 and to data from elsewhere at the NTS in Figure 7-5. Where 
they could be estimated, the 95 percent confidence limits for the mean logarithm of the 
permeability data also are shown in Figures 7-4 and 7-5. For the Calico Hills Formation, the 
Prow Pass tuff, the Bullfrog tuff, the Tram tuff, and the MVA, permeabilities are shown for both 
the single-hole and for the cross-hole tests at the C-wells complex. 
The calibrated permeabilities for the Calico Hills Formation, the Pre-Lithic Ridge tuffs, and the 
carbonate aquifer are within the 95 percent confidence limits of the mean permeabilities 
estimated from single-hole pump test analyses at Yucca Mountain (Figure 7-4). The calibrated 
permeability for the Bullfrog tuff is within the 95 percent confidence limits of the 
mean-measured permeability determined from the cross-hole tests. The calibrated permeability 
of the Prow Pass tuff is slightly higher than the mean permeability estimated from the cross-hole 
tests, whereas the calibrated permeability of the Tram tuff is between the mean permeabilities 
estimated for the unit from the single-hole and cross-hole tests (Figure 7-4). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-30 November 2004 
Source DTN: SNT05082597001.003 [DIRS 129714]. 
Figure 7-4. Logarithms of Permeabilities Estimated During Model Calibration Compared to Mean 
Logarithms of Permeability Determined from Pump-Test Data from Yucca Mountain 
The mean measured permeability of the carbonate aquifer is higher elsewhere at the NTS than 
either the mean-measured permeability at Yucca Mountain or the calibrated permeability for the 
carbonate aquifer (Figures 7-4 and 7-5). The calibrated permeabilities for the alluvial aquifer 
and the lava flow aquifer are within or very close to the 95 percent confidence limits for the 
mean permeabilities of these units. The calibrated permeability for the upper volcanic aquifer is 
about two orders of magnitude less than the mean-measured permeability of this unit. 
Overall, the calibrated permeabilities are consistent with most of the permeability data from 
Yucca Mountain and elsewhere at the NTS, except for the upper volcanic aquifer. The calibrated 
permeability of the Tram tuff is lower than the mean permeability derived from the cross-hole 
tests but higher than the permeability estimated from the single-hole tests. The relatively high 
permeability estimated for the Tram tuff from the cross-hole tests may be at least partially 
attributable to local conditions at the site of these tests. A breccia zone is present in the Tram 
tuff at boreholes UE-25 c#2 and UE-25 c#3 (Geldon et al. 1997 [DIRS 100397], Figure 3), 
which is a factor that may have caused a local enhancement in the permeability of the Tram tuff. 
The permeability data recently obtained from single-hole and cross-hole testing in the Alluvial 
Testing Complex have not been included in Figure 7-5. As indicated in Section 7.2.2.1, while 
the permeabilities reported from the single-hole tests for the alluvial materials are about an order 
of magnitude less than the calibrated value, the cross-hole tests yield a permeability 
measurement similar to the calibrated permeability values for the alluvial aquifer. 
Model Calibration 
upper limit 
mean 
lower limit 
Single-Hole 
Tests 
Cross-Hole 
Tests 
Calico Hills Formation 
Prow Pass Tuff 
Bullfrog Tuff 
Tram Member 
(Crater Flat Tuff) 
Lithic Ridge Tuff 
Older Tuffs 
Middle Volcanic Aquifer 
Mixed Tuffs 
Carbonate Aquifer 
Hydrogeologic Unit 
Logarithm of Permeability (m2) 
-10 
-11 
-12 
-13 
-14 
-15 
-16 
-17 
-18
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-31 November 2004 
DTN: SNT05082597001.003 [DIRS 129714]. 
Figure 7-5. Logarithms of Permeabilities Estimated During Model Calibration Compared to Mean 
Logarithms of Permeability Determined from Pump-Test Data from the NTS 
While the calibrated permeability of the many geologic units and features represented in the SZ 
site-scale flow model may indirectly influence to a limited extent the specific discharge predicted 
by the SZ site-scale model, the calibrated permeabilities of those geologic units along the flow 
path from the repository to the compliance boundary most directly determine the specific 
discharge predicted by the SZ site-scale model. Particle tracking using the SZ site-scale model 
(see Section 7.2.3.1) indicates that fluid particles migrating from the repository generally travel 
downward until they reach the Crater Flat Bullfrog unit. Because of the high permeability of the 
Bullfrog unit, the particles remain in that unit until reaching the southern end. At this point, fluid 
particles generally enter the alluvial portion of the flow system after briefly transitioning the 
upper volcanic confining unit. The flow path through the alluvial deposits is represented in the 
SZ site-scale model by the alluvial uncertainty zone and the lower Fortymile Wash zone. Thus, 
those calibrated permeabilities that most directly control the prediction of specific discharge by 
the SZ site-scale model are those for the Bullfrog unit and the alluvial uncertainty and lower 
Fortymile Wash zones. 
The calibrated value for the Bullfrog unit was 1.54 x 10-11 m2 (see Table 6-21). As shown in 
Table 6-24, the mean permeability for the cross-hole measurements of the Bullfrog unit at Yucca 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-32 November 2004 
Mountain was 1.37 x 10-11 m2. Thus, the calibrated permeability for the Bullfrog unit was only 
12 percent greater than the mean of the measured value. 
As indicated in Section 7.2.2.3.2, cross-hole tests have been performed in the alluvial material at 
the ATC in borehole NC-EWDP-19D. Borehole NC-EWDP-19D is located in the southern 
portion of the alluvial uncertainty zone established in the SZ site-scale model. The calibrated 
permeability for the alluvial uncertainty zone was 3.20 x 10-12 m2. The permeability measured 
during the cross-hole tests at NC-EWDP-19D was 2.7 x 10-12 m2. Thus, the calibrated 
permeability for the alluvial uncertainty zone was only 19 percent greater than the measured 
value. 
Because new waterlevel data and permeability measurements are available at the ATC, 
predicted and observed values of hydraulic gradient and permeability at this location can be used 
to calculate specific discharge. These calculated specific discharge values can be compared to 
evaluate their combined impact on specific discharge for purposes of postmodel development 
validation. As previously discussed in Section 7.1, the predicted hydraulic gradient between 
WT-3 and 19P/2D is only 7 percent greater that the observed gradient between these two 
locations (see Table 7-3). As indicated above, the calibrated permeability for the Alluvial 
Uncertainty Zone was 19 percent greater than the measured value at the ATC. Since the 
combined effect of the differences between predicted and observed values of these parameters on 
specific discharge is the product of their individual impacts, the calculated specific discharge 
based on the predicted value of hydraulic gradient and the calibrated value of permeability is 
only 27 percent greater than the value calculated using the respective observed values of these 
parameters. This result meets the validation criteria of being within a factor of 3 
(BSC 2004 [DIRS 170115], Section 2.2) used in the SZ transport abstraction model. 
The 18-km compliance region described in Section 6.8.5.2 and the SZ transport abstraction 
model (BSC 2004 [DIRS 170042]) are strongly influenced by groundwater flow in alluvium. 
Estimates of groundwater-specific discharge in the SZ were recently obtained from field-testing 
at the ATC (BSC 2004 [DIRS 170010], Section 6.5.5). The ATC is located approximately 
18 km from Yucca Mountain at the boundary of the accessible environment as specified in 
10 CFR 63.302 (10 CFR Part 63 [DIRS 156605]). The ATC testing was performed in the 
alluvium aquifer. Estimates of groundwater specific discharge at the ATC range from 1.2 m/yr 
to 9.4 m/yr. For the details of flow porosity in alluvium, see DTN: LA0303PR831231.002 
([DIRS 163561]) and BSC (2004 [DIRS 170010], Section 6.4). For the expected flow porosity 
in the alluvium of 0.18, the test-derived specific discharge ranges from 2.4 m/yr to 7.3 m/yr. The 
simulated average specific discharge in this region of the SZ system, using the SZ transport 
abstraction model, ranges from 1.9 m/yr to 3.2 m/yr for differing values of horizontal anisotropy 
in permeability ranging from 0.05 to 20 (BSC 2004 [DIRS 170010], Section 6.2.6). For the 
mean horizontal anisotropy, the simulated average specific discharge is approximately 2.8 m/yr 
for the ATC test location (BSC 2004 [DIRS 170042], Section 6.5.1.2). This specific discharge is 
within a factor of 1.2 of the lower end of test-derived value (2.4 m/yr) and a factor 2.6 of the 
upper end value (7.3 m/yr), which meets the validation criterion of being within a factor of 3 
(BSC 2004 [DIRS 170115], Section 2.2). Therefore, the data from the ATC field-testing both 
constitute new specific discharge in the SZ information and significantly reduce uncertainty in 
the specific discharge relative for use in SZ transport abstraction model. The remaining 
uncertainty is propagated accordingly into the SZ transport abstraction model (BSC 2004 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-33 November 2004 
[DIRS 170042]), Section 6.5.2). Specifically, an uncertainty distribution in specific discharge is 
constructed, in which 80 percent of the probability is between one-third and three times the best 
estimate of specific discharge, with an additional 10 percent assigned to the lower tail of 1/30 of 
the expected value and 10 percent to the upper tail of 10 times the expected value of specific 
discharge. Additionally, the uncertainty in effective porosity is captured through the use of a 
truncated normal distribution as used in the SZ transport abstraction model (BSC 2004 
[DIRS 170042], Section 6.5.2). The details of the uncertainty distributions of specific discharge 
and effective porosity in the alluvium and their associated sampling techniques are contained in 
the abstraction model, Sections 6.5.2.1 and 6.5.2.3, respectively. 
7.2.3 Comparison of Hydrochemical Data Trends with Calculated Particle Pathways 
The SZ transport model was used to simulate the movement of a conservative tracer from 
various segments along the boundaries in the model. The location of these boundary segments 
and their numerical designations in the model are shown in Figure 6-42. The goal of these 
simulations was to provide an understanding of where groundwater at any location in the flow 
system may have originated and to what extent groundwaters originating from various locations 
may mix. These simulation results are then qualitatively evaluated in the context of the 
understanding gained from the analysis of the hydrochemical and isotopic data discussed in 
detail in Appendix A. 
Groundwater flow paths and mixing zones were identified in the analyses of the areal 
distributions of measured and calculated geochemical and isotopic parameters, scatterplots, and 
inverse mixing and reaction models with PHREEQC (BSC 2002 [DIRS 157837]). This 
summary describes the basis for the flow paths drawn in Section 7.2.3.1. 
Flow paths of tracer particles were calculated for the SZ site-scale transport model. The particles 
were started in the vicinity of the repository footprint and allowed to transport downstream to the 
compliance boundary. These flow pathways are compared to flow paths deduced from 
hydrochemistry data in Figure 7-6 . Flow paths deduced from hydrochemistry data were 
deduced in the context of the hydraulic gradient and considering the possibility that flow paths 
can be oblique to the potentiometric gradient because of anisotropy in permeability. Theses flow 
paths were drawn by first using chemical and isotopic constituents generally considered to 
behave conservatively in groundwater such as the chloride (Cl-), sulphate (SO4
2-) ions. However, 
because no single chemical or isotopic species varies sufficiently to determine flow paths 
everywhere in the study area, multiple lines of evidence were used to construct the flow paths. 
This evidence includes the areal distribution of chemical and isotopic species, sources of 
recharge, groundwater ages and evaluation of mixing/groundwater evolution through 
scatterplots, and inverse mixing and reaction models as presented in the previous sections. The 
derivation of flow pathways from hydrochemical data is developed in detail in Appendix A and 
summarized in Section A6.6.11 
Of particular interest are the flow paths labeled #2 and #7 from this analysis (Figure 7-6). Flow 
Path #7, originates in the vicinity of the repository footprint and overlaps the model-calculated 
flow paths Figure 7-6. Flow Path #2 is also of interest here, although it originates northeast of 
the repository, because it closely bounds Flow Path #7 to the east. Although flow pathways 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-34 November 2004 
derived from hydrochemical data do not originate in the exact same location as particle tracks 
drawn using the site scale model, the paths converge east and south of the repository. 
7.2.4 Thermal Modeling 
Measurements of temperature in the SZ constitute an independent data set that was not used in 
the calibration of the SZ site-scale flow model and may be used to support the validation of the 
flow model. The transport of heat in the geosphere occurs generally upward toward the Earths 
surface, leading to higher temperatures with depth. However, heat is also redistributed by 
groundwater flow, and temperature can potentially serve as a tracer for the movement of 
groundwater in the SZ. To evaluate heat transport in the SZ, modeling of heat transport through 
conduction only and through conduction with convective transport was undertaken. The 
validation of the SZ site-scale flow model using simulations of heat transport and measured 
values of temperature in the SZ is documented in the following section. Modeling of heat 
transport through conduction only is presented first, followed by a presentation of modeling of 
heat transport through both conduction and convection. The direct comparison of temperature 
with groundwater movement is complicated by spatial uncertainty in thermal properties, 
overburden thickness, and heat flux. Despite these inherent limitations, an acceptable 
comparison between observed and simulated temperatures was achieved. The work presented in 
this section is taken from the paper Arnold et al. (2003 [DIRS 164473]) and is not used for any 
other purpose than to provide additional insight into the SZ site-scale flow model. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-35 November 2004 
Source: See Appendix A, Figure A6-62 
NOTE: In red, flow paths calculated from hydrochemistry data; in black, flow paths calculated for tracer particles 
starting at the repository footprint. UTM = Universal Transverse Mercator 
Figure 7-6. Transport Pathways Deduced from Hydrochemistry Data, Compared to Particle Pathways 
Calculated for the Saturated Zone Site-Scale Transport Model 
7.2.4.1 Conduction-Only Modeling 
Heat transport in the geosphere is a function of thermal conduction and advective movement 
with groundwater flow. Simulation of coupled groundwater flow and heat transport in the SZ is 
a more complete description of natural geothermal processes in the SZ system. Simulations of 
heat conduction alone are used to assess the relative importance of conduction with regard to the 
observed temperatures in the system. In addition, the conduction-only model of the SZ is 
calibrated with respect to observed temperatures and provides a starting point for coupled 
thermal simulations that have been optimized with regard to thermal conduction. 
The SZ site-scale flow model is used as the basis for the modeling of heat conduction. The 
model domain and definitions of the hydrogeologic units are retained from the SZ site-scale flow 
model. Values of thermal conductivity are designated on a unit-by-unit basis. The thermal 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-36 November 2004 
boundary conditions on the bottom and top boundaries of the SZ site-scale flow model are 
defined and adjusted in the thermal calibration process. 
7.2.4.1.1 Temperature and Thermal Properties Data 
Data on temperatures in the SZ are taken from temperature profiles measured in wells within the 
SZ site-scale flow model area. These data are from Yucca Mountain Project wells and from the 
newer Nye County Early Warning Drilling Program wells and are compiled in Table 7-9. The 
temperature data in Table 7-9 were extracted at 200-m intervals from these temperature logs, 
starting at the water table. A total of 94 observed temperatures in 35 wells were obtained. 
Table 7-9. Temperature Data from Boreholes 
Well 
ID 
UTM Easting 
(m) 
UTM Northing 
(m) 
Elevation 
(m) elative 
to mean sea 
level 
Temperature 
(C) 
Data Tracking 
Number* 
USWG-1 548306 4080016 754 29.6 GS950408318523.001 
USWG-1 548306 4080016 554 35.8 GS950408318523.001 
USWG-1 548306 4080016 354 39.2 GS950408318523.001 
USWG-1 548306 4080016 154 44.9 GS950408318523.001 
USWG-1 548306 4080016 -46 50.4 GS950408318523.001 
USWG-1 548306 4080016 -246 55.7 GS950408318523.001 
USWG-1 548306 4080016 -446 62.1 GS950408318523.001 
USWG-2 548143 4082542 1028 29.6 GS950408318523.001 
USWG-2 548143 4082542 828 32.3 GS950408318523.001 
USWG-2 548143 4082542 628 38.4 GS950408318523.001 
USWG-2 548143 4082542 428 46.6 GS950408318523.001 
USWG-2 548143 4082542 228 55.1 GS950408318523.001 
USWG-3 547543 4074619 729 33 GS950408318523.001 
USWG-3 547543 4074619 529 35.3 GS950408318523.001 
USWG-3 547543 4074619 329 39.7 GS950408318523.001 
USWG-3 547543 4074619 129 43 GS950408318523.001 
USWG-4 548933 4078602 729 30 GS950408318523.001 
USWG-4 548933 4078602 529 34.5 GS950408318523.001 
USWH-1 548727 4079926 730 32.8 GS950408318523.001 
USWH-1 548727 4079926 530 35.4 GS950408318523.001 
USWH-1 548727 4079926 330 39.3 GS950408318523.001 
USWH-1 548727 4079926 130 44.2 GS950408318523.001 
USWH-1 548727 4079926 -70 50.1 GS950408318523.001 
USWH-1 548727 4079926 -270 56.2 GS950408318523.001 
USWH-1 548727 4079926 -470 61.6 GS950408318523.001 
USWH-3 547562 4075759 732 33.3 GS950408318523.001 
USWH-3 547562 4075759 532 37.2 GS950408318523.001 
USWH-3 547562 4075759 332 41.1 GS950408318523.001 
USWH-4 549188 4077309 730 30.7 GS950408318523.001 
USWH-4 549188 4077309 530 32.8 GS950408318523.001 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-37 November 2004 
Table 7-9. Temperature Data from Boreholes (Continued) 
Well 
ID 
UTM Easting 
(m) 
UTM Northing 
(m) 
Elevation 
(m) elative 
to mean sea 
level 
Temperature 
(C) 
Data Tracking 
Number* 
USWH-4 549188 4077309 330 33.7 GS950408318523.001 
USWH-4 549188 4077309 130 38.3 GS950408318523.001 
USWH-4 549188 4077309 30 40.2 GS950408318523.001 
USWH-5 547668 4078841 774 35.1 GS950408318523.001 
USWH-5 547668 4078841 574 37.1 GS950408318523.001 
USWH-5 547668 4078841 374 40.3 GS950408318523.001 
USWH-6 546188 4077816 776 34 GS950408318523.001 
USWH-6 546188 4077816 576 36.1 GS950408318523.001 
USWH-6 546188 4077816 376 44 GS950408318523.001 
USWH-6 546188 4077816 176 51.2 GS950408318523.001 
UE-25b1H 549949 4078423 731 31.8 GS950408318523.001 
UE-25b1H 549949 4078423 531 34.6 GS950408318523.001 
UE-25b1H 549949 4078423 331 35.4 GS950408318523.001 
UE-25b1H 549949 4078423 131 39.2 GS950408318523.001 
UE-25p1 551501 4075659 730 33.6 GS950408318523.001 
UE-25p1 551501 4075659 530 38.2 GS950408318523.001 
UE-25p1 551501 4075659 330 41.9 GS950408318523.001 
UE-25p1 551501 4075659 130 48.1 GS950408318523.001 
UE-25p1 551501 4075659 -70 55.6 GS950408318523.001 
UE-25p1 551501 4075659 -270 57.5 GS950408318523.001 
UE-25p1 551501 4075659 -470 55.4 GS950408318523.001 
USWVH-1 539976 4071714 898 27 GS930208318523.001 
USWVH-1 539976 4071714 698 32 GS930208318523.001 
USWVH-1 539976 4071714 498 35 GS930208318523.001 
USWVH-1 539976 4071714 298 36 GS930208318523.001 
USWVH-2 537738 4073214 811 27 GS930208318523.001 
USWVH-2 537738 4073214 611 30 GS930208318523.001 
USWVH-2 537738 4073214 411 35 GS930208318523.001 
USWVH-2 537738 4073214 211 36 GS930208318523.001 
USWVH-2 537738 4073214 11 38 GS930208318523.001 
USWVH-2 537738 4073214 -189 52 GS930208318523.001 
J-13WW 554017 4073517 729 30.2 GS950408318523.001 
J-13WW 554017 4073517 529 30.7 GS950408318523.001 
J-13WW 554017 4073517 329 33.1 GS950408318523.001 
J-13WW 554017 4073517 129 35.8 GS950408318523.001 
USWWT-1 549152 4074967 731 30.1 GS950408318523.001 
USWWT-2 548595 4077028 730 31.5 GS950408318523.001 
UE-25WT3 552090 4072550 730 33.1 GS950408318523.001 
UE-25WT4 550439 4079412 728 31.4 GS950408318523.001 
UE-25WT6 549352 4083103 1029 28.4 GS950408318523.001 
USWWT-7 546151 4075474 776 33.8 GS950408318523.001 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-38 November 2004 
Table 7-9. Temperature Data from Boreholes (Continued) 
Well 
ID 
UTM Easting 
(m) 
UTM Northing 
(m) 
Elevation 
(m) elative 
to mean sea 
level 
Temperature 
(C) 
Data Tracking 
Number* 
USWWT-10 545964 4073378 775 38.8 GS950408318523.001 
USWWT-11 547542 4070428 730 35.2 GS950408318523.001 
UE-25WT12 550168 4070659 730 32.9 GS950408318523.001 
UE-25WT13 553730 4075827 729 28.5 GS950408318523.001 
UE-25WT14 552630 4077330 730 29.9 GS950408318523.001 
UE-25WT15 554034 4078694 729 27.5 GS950408318523.001 
UE-25WT16 551146 4081234 737 32.3 GS950408318523.001 
UE-25WT17 549905 4073307 729 31.1 GS950408318523.001 
UE-25WT18 549468 4080238 731 31.2 GS950408318523.001 
NC-EWDP-1S 536771 4062498 787 21.7 MO0008NYE02997.033 
NC-EWDP- 
2DB 547744 4057164 706 24.1 MO0101NYE03692.071 
NC-EWDP-3D 541273 4059444 717 26.6 MO0008NYE02997.033 
NC-EWDP-3D 541273 4059444 517 26.3 MO0008NYE02997.033 
NC-EWDP-3D 541273 4059444 317 28.4 MO0008NYE02997.033 
NC-EWDP-3D 541273 4059444 117 42.3 MO0008NYE02997.033 
NC-EWDP- 
5SB 555676 4058229 724 29.2 MO0101NYE03452.061 
NC-EWDP-7S 539558 4064317 830 24.5 MO0101NYE03456.065 
NC-EWDP-7S 539558 4064317 630 31.7 MO0101NYE03456.065 
NC-EWDP- 
12PA 536905 4060766 723 32.7 MO0101NYE03453.062 
NC-EWDP- 
12PC 536871 4060808 721 29.5 MO00101NYE03455.064. 
NC-EWDP- 
19P 549237 4058265 713 26.2 MO0409NYE06210.225 
UE-25a#1 549925 4078330 731 31.5 GS950408318523.001 
UE-25a#1 549925 4078330 531 34.1 GS950408318523.001 
NOTE: The DTNs listed in the table: DTN: GS950408318523.001 [DIRS 107244]; 
DTN: MO0008NYE02997.033 [DIRS 155290]; DTN: GS930208318523.001 [DIRS 145763]; and the 
Nye Co. web site Nye County Nuclear Waste Repository Project Office 2000 [DIRS 149364] are the 
sources of information for each entry. Five different parts of [DIRS 149364] provide data used in this 
table. This table is used as reference only. 
UTM = Universal Transverse Mercator 
Values of thermal conductivity for the hydrogeologic units in the conduction-only model are 
taken from a variety of sources and are listed in Table 7-10. For hydrogeologic units that are 
generally stratified and for which multiple thermal conductivity measurements are available, 
vertical and horizontal thermal conductivity are estimated separately. Harmonic averaging is 
appropriate for effective conductivity in the vertical direction in which stratified variations in 
conductivity occur in series. Arithmetic averaging is appropriate for effective conductivity in the 
horizontal direction in which variations in conductivity generally occur in parallel. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-39 November 2004 
Table 7-10. Thermal Conductivity of SZ Hydrogeologic Units 
Model 
Zone 
Number Hydrogeologic Unit 
Horizontal 
Thermal 
Conductivity 
(W/mK) 
Vertical 
Thermal 
Conductivity 
(W/mK) 
Reference of 
Corroborative Data 
2 
Granite 
2.40 2.40 
Sass et al. 1984, Table 1, p. 17 
[DIRS 153174] 
3 
Lower Clastic Confining Unit 
2.49 2.49 
Sekiguchi 1984, Table 1, p.73 
[DIRS 163363] 
4 
Lower Carbonate Aquifer 
4.95 4.55 
Sass et al. 1988, Section 3-5, 
p.118 [DIRS 100644] 
5 
Upper Clastic Confining Unit 
2.49 2.49 
Sekiguchi 1984, Table 1, p.73 
[DIRS 163363] 
6 
Lower Carbonate Aquifer 
(Thrust) 4.95 4.55 
Sass et al. 1988, Section 3-5, 
p.118 [DIRS 100644] 
7 
Upper Carbonate Aquifer 
3.61 3.03 
Ryder 1997, Section 3.2, p.10 
[DIRS 163364] 
8 
Undifferentiated Valley Fill 
(North) 1.60 1.60 
* 
9 
Older Volcanic Confining Unit 
1.87 1.86 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
10 
Older Volcanic Aquifer 
2.00 2.00 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
11 
Lower Volcanic Confining Unit 
1.87 1.86 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
12 
Tram Tuff 
1.75 1.72 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
13 
Bullfrog Tuff 
1.63 1.60 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
14 
Prow Pass Tuff 
1.45 1.43 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
15 
Upper Volcanic Confining Unit 
1.21 1.20 
Sass et al. 1988, Tables 3-1, 3-2, 
and 3-3, pp. 107, 110, 113 
[DIRS 100644] 
16 
Upper Volcanic Aquifer 
1.67 1.56 
Brodsky et al. 1997, Table A-3, 
p.A12 [DIRS 100653] 
17 
Lava Flow Aquifer 
2.09 2.09 
Lagedrost and Capps 1983, 
Table 26, p. 70 [DIRS 163366] 
18 
Limestone Aquifer 
3.61 3.03 
Ryder 1997, Section 3.2, Table 1, 
p. 10 [DIRS 163364] 
20 
Valley Fill Aquifer 
1.00 1.00 
Wollenberg et al. 1983 p. 9 
[DIRS 163359] 
23 
Undifferentiated Valley Fill 
(South) 1.00 1.00 
Wollenberg et al. 1983, p. 97 
[DIRS 163359] 
NOTE: *Estimate based on unit consisting predominantly of volcanic material. (W/m-K) = watts per 
meter-degree kelvin 
This table is for reference only. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-40 November 2004 
Sass et al. (1984 [DIRS 153174]) investigated thermal conductivity measurements on several 
rock types, including granite, using the steady state divided bar, line source, and half-space probe 
techniques. Two thermal conductivities are given for granite, at 23C (Sass et al. 
(1984 [DIRS 153174]), p. 17); one derived using the divided bar technique, 2.40 W-m-1K-1, and 
the other, 2.27 W-m-1K-1, using the half-space probe technique. The authors suggest thermal 
conductivity values using the divided bar technique be used for materials that are easily 
machineable, anisotropic, and nonfriable materials. Granite falls within this category. For this 
reason, the YMP regional heat flow model uses 2.40 W-m-1K-1 as the thermal conductivity of 
granite. 
Sekiguchi (1984 [DIRS 163363]) presents thermal conductivities for several rock types, 
including silty-sandstone, based on three empirical equations, all a function of porosity, fluid 
type, and mineralogy. He determined a thermal conductivity range for silty-sandstone of 
which a value listed as the primary thermal conductivity for silty-sandstone is bounded 
(Sekiguchi 1984 [DIRS 163363], Table 1). Consequently, it is believed that 2.49 W/mK (watts 
per meter-degree kelvin), which is the primary thermal conductivity for silty-sandstone given in 
Sekiguchi (1984 [DIRS 163363]), is appropriate for the regional scale geothermal simulations. 
Site-specific thermal conductivity data are reported for dolomite by Sass et al. (1988 
[DIRS 100644]). Thirteen Lone Mountain dolomite core samples were taken from borehole 
UE-25 p#1 at depths 1310.4 m to 1801.6 m. Sass et al. (1988 [DIRS 100644] Appendix 3, 
p. 118, Table 3-5) derived thermal conductivity measurements at ambient room temperatures of 
about 25C. From these values, an harmonic-averaged and an arithmetic effective thermal 
conductivity are developed. The harmonic-averaged thermal conductivity, 4.55 W/mK, is to be 
used for heat flow in the vertical direction; the arithmetic-averaged value, 4.95 W/mK, is to be 
used for heat flow in the horizontal direction. 
There are no site-specific thermal conductivity measurements for limestone. Consequently, 
limestone thermal conductivity derived from similar rock types is used. Limestone has been 
considered as one of the material components to be included in a backfill mixture for Yucca 
Mountain and has been discussed in Ryder (1997 [DIRS 163364], Section 3.2, p. 10). The range 
listed in Ryders 1997 report is based on the authors literature search. Values appropriate for 
temperatures below 50C for limestone thermal conductivity (3.033.61 W/mK) are used in the 
site-scale heat flow model for the vertical and horizontal thermal conductivities. 
There are numerous site-specific thermal conductivity measurements for the various tuff units 
incorporated in the analysis. These values are reported by Sass et al. (1988 [DIRS 100644]) and 
Brodsky (1997 [DIRS 100653]). Two effective thermal conductivities are derived, one in the 
vertical direction, the other in the horizontal direction, from cores lithologies representative of 
each hydrogeologic unit. Thermal conductivity in the vertical direction is derived by first 
harmonically averaging thermal conductivities for each individual borehole. Then the harmonic 
averages from individual boreholes are arithmetically averaged. Thermal conductivity in the 
horizontal direction is derived by simply arithmetically averaging data from the same 
hydrogeologic units. The number of samples used in the analysis ranged from 7 for the Prow 
Pass tuff to 58 for the upper volcanic aquifer. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-41 November 2004 
Thermal conductivity measurements for 11 core samples from three boreholes drilled through the 
Pomona Member Basalt, located in Washington State, are used to derive an effective basalt 
thermal conductivity. Thermal conductivity measurements were taken at temperatures ranging 
between 21C to 50C. To derive a thermal conductivity for 30C, a simple linear interpolation 
for thermal conductivity values measured at ~22C to 50C is used. The 11 interpolated values 
are arithmetically averaged resulting in a thermal conductivity of 2.09 W/mK. 
There are no site-specific data on the thermal conductivity of saturated alluvium. Smyth et al. 
(1979 [DIRS 163360]) report values of thermal conductivity ranging from 0.5 to 1. W/mK for 
soils, indurated, and unconsolidated alluvium at varying degrees of saturation. Wollenberg et al. 
(1983 [DIRS 163359], p. 97) give an estimated value of 1.0 W/mK for the thermal conductivity 
of typical alluvium under saturated or near-saturated conditions. For the units that are 
predominantly alluvium, 1.0 W/mK is taken as a representative estimate of the thermal 
conductivity. Because considerable uncertainty exists in the thermal conductivity of alluvium in 
the SZ site-scale flow model domain, sensitivity analyses were conducted to evaluate the impact 
of this parameter on the calibration of the conduction-only model, as described later. 
7.2.4.1.2 Thermal Conduction Model Setup 
The FEHM input files for the SZ site-scale flow model are used as the starting point for the SZ 
site-scale thermal conduction model. Input macros related to fluid flow are removed from the 
input file, a heat-conduction-only solution is indicated, and thermal boundary conditions are 
added. The lateral boundaries of the SZ site-scale thermal conduction model are set as no 
thermal flow. This is appropriate, given the primarily vertical nature of geothermal heat 
transport and the relatively thin dimension of the model in the vertical direction (2.75 km thick x 
30 km x 45 km). The bottom boundary is specified heat flux to reflect upward heat transport 
from the deeper crust. The upper boundary condition is temperature-dependent heat flux, in 
which the heat flux to the land surface is calculated as a function of the simulated temperature at 
the water table and the specified temperature at the land surface. 
7.2.4.1.2.1 Thermal Boundary Conditions on the Upper Boundary 
The thermal boundary condition at the upper boundary of the SZ site-scale thermal conduction 
model requires that the temperature at the land surface and the effective conductance from the 
water table to the land surface be specified. The temperature at the land surface is specified 
based on an estimate of the average annual surface temperature. The effective thermal 
conductance of the UZ is a function of several factors, including thickness of the UZ, rock type, 
and downward percolation of groundwater through the UZ; however, only thickness of the UZ is 
included here. The spatially varying effective thermal conductance of the UZ is estimated in the 
calibration process, as explained later. 
The average annual surface temperature for the SZ site-scale thermal model domain is estimated 
using a relationship relating temperature to elevation (Section 6.5.3.7). This simple linear 
relationship for average surface temperature is: 
) ( ref s ref s Z Z T T - - = . (Eq. 7-1) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-42 November 2004 
where 
Ts is the average surface temperature 
Tref is the average temperature at a reference location 
. is the rate of change in temperature with elevation 
Zs is the surface elevation 
Zref is the surface elevation at the reference location. 
Using values of mean surface temperature and elevations from the locations of boreholes NRG-6 
and NRG-7 (DTN: GS950208312232.003 [DIRS 105572]), the value of . is 0.009C/m 
(Section 6.5). The reference average surface temperature and reference elevation at the location 
of borehole NRG-6 are 18.23C and 1231 m, respectively. 
This relationship is applied to the SZ site-scale thermal model domain to estimate the average 
annual surface temperature, as shown in Figure 7-7. Estimated average surface temperature 
varies as a function of elevation from about 10C in northern parts of the area to greater than 
22C at the lower elevations in the southern part of the domain. The spatially varying values of 
estimated average surface temperature shown in Figure 7-7 are used as the upper boundary 
condition of the SZ site-scale thermal model. 
The thermal conductance of the UZ at the upper boundary of the SZ site-scale thermal 
conduction model is inversely proportional to the thickness of the UZ, which varies considerably 
across the area of the model. The UZ acts as a thermal blanket to geothermal heat flow from 
the SZ, so the higher conductance occurs where the UZ is thin and lower conductance occurs 
where the UZ is relatively thick. Figure 7-8 shows a plot of the thickness of the UZ, which 
varies from less than 50 m in the south and in Fortymile Canyon to greater than 1,000 m in the 
north. The values of UZ thickness shown in Figure 7-8 are used to calculate spatially varying 
values of thermal conductance for the upper boundary condition in the SZ site-scale thermal 
conduction model. 
Considerable uncertainty exists in the effective thermal conductivity of the UZ. In addition, 
thermal conductivity of the UZ varies as a function of rock type and heat flow may be influenced 
by downward percolation of groundwater in the UZ, as noted above. Because of these 
uncertainties, the effective thermal conductance at the upper boundary is treated as a calibration 
parameter in the heat conduction-only modeling for the SZ. The inverse proportionality to UZ 
thickness is preserved in the calibration process, but the overall effective thermal conductance is 
adjusted proportionally during thermal calibration. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-43 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
Temperature (C) 
Source: Arnold et al. 2003 [DIRS 164473]. 
UTM = Universal Transverse Mercator 
Figure 7-7. Computed Average Annual Surface Temperature for the SZ Site-Scale Thermal Model Area 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-44 November 2004 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
0
100 
200 
300 
400 
500 
600 
700 
800 
900 
1000 
Depth (m) 
Source: Arnold et al. 2003 [DIRS 164473]. 
UTM = Universal Transverse Mercator 
Figure 7-8. Depth to the Water Table in the SZ Site-Scale Flow Model Area 
7.2.4.1.2.2 Thermal Boundary Conditions on the Lower Boundary 
The lower thermal boundary condition of the SZ site-scale thermal conduction model is assigned 
a uniform value of specified heat flux. Variations in the geothermal heat flux may occur at the 
scale of the SZ site-scale flow model domain; however, there is not sufficient information on 
variations in deep heat flow to justify assigning spatial variations in heat flux at the bottom 
boundary of the model. The lower boundary of the SZ site-scale thermal conduction model is 
relatively deep at 2,750 m below the water table, so variations in heat flux due to topographic 
effects and groundwater flow are significantly less than at shallower depths. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-45 November 2004 
The estimated geothermal heat flux from measurements of temperature profiles in wells at Yucca 
Mountain is about 40 mW/m2 (Sass et al. 1988, p. 2 [DIRS 100644]). This value of heat flux is 
considerably lower than the regional average of about 85 mW/m2. Because there is considerable 
uncertainty in the appropriate value of heat flux at the lower boundary of the SZ site-scale 
thermal conduction model, this parameter is varied in the thermal calibration process to match 
the observed temperatures. 
7.2.4.1.3 Thermal Model Calibration 
The SZ site-scale thermal conduction model was calibrated by adjusting the upper and lower 
thermal boundary conditions in a trial-and-error method. (The simulated temperatures at the 
water table in the calibrated conduction-only model are shown in Figure 7-9.) The model was 
run to steady-state thermal conditions and the simulated temperatures were compared to the 
observed temperatures in a cross plot, such as shown in Figure 7-10. The calibration process 
sought to minimize the coefficient of determination (R2) for this cross plot. The calibration also 
attempted to place the least-squares line fit to the cross plot along a 45oline, as shown by the 
dashed red line in Figure 7-10. Precise optimization of the conduction-only model was not 
required for the purposes of this analysis because the ultimate goal was to examine coupled 
groundwater flow and heat transport. 
The best calibration of the SZ site-scale thermal conduction model is obtained with a uniform 
heat flux of 35 mW/m2 at the lower boundary and an equivalent thermal conductivity of 
0.3 W/mK for the UZ at the upper boundary. The calibrated value of the heat flux at the lower 
boundary of 35 mW/m2 is somewhat lower than the estimate from Sass et al. (1988 
[DIRS 100644], Section 2-17), but is within the estimated range of error (40  9 mW/m2) from 
that study. The calibrated value of the equivalent thermal conductivity for the UZ is quite low 
relative to the units in the SZ. However, this equivalent value may also account for the effects of 
unsaturated conditions, variations in rock type, and percolation of groundwater. 
As mentioned above, the simulated temperatures at the water table in the calibrated 
conduction-only model are shown in Figure 7-9. The values of simulated temperature are 
projected onto -the water table surface, and the topographic surface is shown in this figure. 
There is considerable variation in the simulated temperature at the water table, primarily as a 
function of the UZ. 
The higher simulated temperatures correspond to the relatively thick UZ under Yucca Mountain 
in the north-central portion of the area and under the Calico Hills in the northeastern part of the 
model. The lower simulated temperatures occur in areas where the water table is closer to the 
land surface, in the southern part of the model, and under Fortymile Canyon in the north. The 
pattern of simulated temperatures at the water table is influenced to a lesser extent by refraction 
of heat flow in the lower carbonate aquifer with its higher thermal conductivity. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-46 November 2004 
16 
18 
20 
22 
24 
26 
28 
30 
32 
34 
36 
38 
Temperature (C) 
Source: Arnold et al. 2003 (DIRS 164473). 
NOTE: Temperature is in C. 
Figure 7-9. Simulated Temperatures at the Water Table for the Thermal Conduction Model
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-47 November 2004 
20 30 40 50 60 70 
Simulated Temperature (C) 
20 
30 
40 
50 
60 
70 
Observed Temperature (C) 
Source: Arnold et al. 2003 [DIRS 164473]. 
NOTE: Temperatures are in C. 
Figure 7-10. Simulated Temperatures vs. Observed Temperatures for the Thermal Conduction Model 
A plot of the 94 observations of temperatures in wells versus simulated temperatures for the 
calibrated thermal conduction model is shown in Figure 7-10. This cross plot indicates that there 
is generally good agreement between observed and simulated temperatures in the model. The R2 
value for these results is 0.80. There is an apparent tendency for the calibrated model to 
underestimate temperatures between 20C and 35C, to overestimate temperatures between 35C 
and 50C, and to underestimate temperatures over 50C. 
The residuals in simulated temperature are defined as the simulated temperature minus the 
observed temperature at a given location. A histogram of the residuals in simulated temperature 
in the calibrated SZ site-scale conduction-only model is shown in Figure 7-11. These residuals 
are approximately normally distributed, with maximum errors in simulated temperature of less 
than 10C. The average residual is 0.3C. A majority of the simulated temperatures is within 
3C of the observed temperature at that location. These characteristics of the residuals indicate 
that the calibrated heat conduction-only model is fairly accurate and unbiased with regard to 
errors in simulated temperature. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-48 November 2004 
-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 
Temperature Residual (C) 
0
4
8 
12 
16 
20 
Frequency 
Source: Arnold et al. 2003 (DIRS 164473). 
NOTE: Temperature is in C. 
Figure 7-11. Histogram of Residuals in Simulated Temperature for the Thermal Conduction Model 
The spatial distribution of residuals in simulated temperature at the water table is examined in 
the map shown in Figure 7-12. This figure indicates that there is some systematic pattern to the 
spatial distribution of residuals in simulated temperature. The positive residuals tend to cluster 
near and to the east of Yucca Mountain; whereas, the residuals farther to the south and 
immediately to the north of Yucca Mountain tend to be negative. The positive residuals indicate 
that the simulated temperature at the water table is too high. 
One explanation for the clustering of positive residuals near the crest of Yucca Mountain is that 
these are locations of significant downward percolation of groundwater through the UZ. 
Downward percolating groundwater tends to suppress the geothermal gradient and would cause 
lower temperatures at the water table. Because the heat conduction-only model does not account 
for this process at the upper boundary, it tends to overestimate the temperature at these locations, 
leading to the positive residuals. The negative residuals may correspond to locations at which 
groundwater flow in the SZ is upward. This process is also not accounted for in the heat 
conduction-only model. Consequently, the simulated temperatures would be too low at these 
locations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-49 November 2004 
Source: Arnold et al. 2003 (DIRS 164473). 
NOTES: Temperatures are in C. UTM = Universal Transverse Mercator 
Figure 7-12. Residuals in Simulated Temperature at the Water Table for the Thermal Conduction Model 
7.2.4.1.4 Sensitivity to Thermal Conductivity in the Alluvium 
Sensitivity of the SZ site-scale heat conduction-only model to the thermal conductivity of the 
alluvium was evaluated using a higher value (1.6 W/mK) and a lower value (0.5 W/mK) for this 
parameter. The results indicate relatively little sensitivity of the model calibration to this 
parameter, with the R2 varying from 0.777 to 0.783 over this range of parameter values. 
Simulated temperatures near the water table are not very sensitive to the thermal conductivity of 
the alluvium below them, but simulated temperatures deeper in the valley-fill regions of the 
model are significantly higher for the lower value of thermal conductivity of the alluvium (and 
vice versa for the higher value). This low sensitivity to the thermal conductivity in the alluvium 
is primarily due to the general lack of deep temperature observations in wells in the alluvium that 
would constrain temperatures. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-50 November 2004 
7.2.4.1.5 Results and Discussion of Conduction-Only Thermal Modeling 
Steady-state heat conduction in the SZ site-scale flow model domain is simulated to assess heat 
transport by conduction only. The resulting calibrated SZ site-scale thermal conduction model 
provides a relatively accurate, unbiased match to the observed temperatures in wells in the Yucca 
Mountain area. Comparison of observed temperatures to simulated temperatures results in a 
value of 0.80 for the R2. The approximately normal statistical distribution of residuals in 
simulated temperature indicates that errors in the model are essentially random and not reflective 
of any systematic misrepresentation of the thermal transport processes in the SZ. There are some 
systematic spatial variations in the residuals in simulated temperatures, but these are generally 
understandable in terms of the coupled groundwater flow and heat transport processes that are 
not included in the conduction-only model. 
Thermal transport in the SZ is dominated by conductive geothermal heat flow at the scale of the 
SZ site-scale flow model domain. The results of the calibration of the conduction-only model 
indicate that at least 80 percent of the variability in the observed temperatures can be explained 
by thermal conduction, based on the coefficient of determination from observed versus simulated 
temperatures. The remaining 20 percent of variability not accounted for in the thermal 
conduction model is probably due to the spatial discretization of the SZ model or spatial 
variability that is not represented in the model. 
The spatial distribution of observations of temperature may limit the interpretation and modeling 
of heat transport in the SZ site-scale flow model area. Most of the temperature logs from wells 
are concentrated near Yucca Mountain, and almost all the measurements at depths of greater than 
a few hundred meters below the water table are in this area. Conclusions regarding the heat flux 
at the bottom boundary of the SZ site-scale flow model are most accurate for the area near Yucca 
Mountain but may be much less applicable elsewhere in the model domain. 
7.2.4.2 Coupled Thermal Modeling 
Coupled thermal modeling of groundwater flow and heat transport provides a more complete 
representation of thermal transport processes in the SZ than the conduction-only modeling. 
Groundwater flow redistributes heat in both the lateral and vertical directions. In addition, 
variations in the density and viscosity of groundwater as a function of temperature influence the 
groundwater flow field. These coupled processes result in a more challenging numerical 
modeling task for the coupled thermal model, relative to the conduction-only model. 
7.2.4.2.1 SZ Site-Scale Coupled Thermal Model Setup 
The SZ site-scale flow model and the SZ site-scale thermal conduction model are used as the 
basis for the modeling of coupled thermal transport. The calibrated upper and lower thermal 
boundary conditions from the conduction-only model are used in the coupled thermal model. 
The lateral groundwater flow boundary conditions of the SZ site-scale flow model are adjusted 
for use in the coupled thermal model. The specified head boundary conditions at the lateral 
boundaries of the SZ site-scale flow model are converted to values of specified pressure for the 
coupled thermal model. The temperature of groundwater flowing into the coupled thermal 
model at the lateral boundaries is specified to be equal to the simulated temperatures at those 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-51 November 2004 
nodes in the SZ site-scale thermal conduction model. Similarly, the specified groundwater flux 
from recharge on the upper boundary of the coupled thermal model is specified to be at the 
simulated temperatures from the conduction-only model. 
The SZ site-scale coupled thermal model is run to steady-state thermal and flow conditions for 
comparison to the observed temperatures in wells. Joint calibration of the coupled thermal 
model to water level and temperature measurements was not possible given the long computer 
run-times necessary to achieve a steady-state solution. Ideally, joint calibration of the SZ 
site-scale model would provide explicit constraints on the groundwater flow field. Nonetheless, 
the uncalibrated coupled heat and groundwater flow model can provide independent validation of 
the flow model and subjective indications to improve the flow model. 
The resulting steady state, simulated temperatures at the water table for coupled groundwater 
flow and thermal transport are shown in Figure 7-13. Simulated temperatures at the water table 
for the coupled model differ significantly from the conduction-only model in the area directly to 
the east of Yucca Mountain and in a small area in Crater Flat. The simulated temperatures are 
generally higher in the area between Yucca Mountain and Fortymile Wash in the coupled model, 
indicating significant upward vertical advective heat transfer in this area of the model. The 
smaller area of higher simulated temperatures in Crater Flat indicates another area of simulated 
upward groundwater flow. 
Results of combining the calibrated SZ site-scale flow model and the calibrated thermal 
conduction model indicate a significant reduction in the R2 of observed and simulated 
temperatures from the conduction-only model (0.62 versus 0.80). A plot of simulated 
temperatures versus observed temperatures for the coupled heat and groundwater flow model is 
shown in Figure 7-14. The statistical distribution of residuals in simulated temperature for the 
coupled model has a broader range than for the conduction-only model with an average 
of 0.13C. Note in Figure 7-14 that the simulated temperatures for the deeper, 
higher temperature measurement locations have both positive and negative residuals from the 
coupled model, whereas, the conduction-only model consistently underestimated the 
temperatures at these locations (Figure 7-10). 
The spatial distribution of residuals in simulated temperature at the water table for the SZ 
coupled thermal model is examined in the map shown in Figure 7-15. The largest positive 
residuals generally occur in the area to the east and southeast of Yucca Mountain and in a 
relatively small area in Crater Flat. The largest negative residuals occur to the north of Yucca 
Mountain. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-52 November 2004 
Simulated 
Temperature (C) 
16 
18 
20 
22 
24 
26 
28 
30 
32 
34 
36 
38 
535000 540000 545000 550000 555000 560000 
UTM Easting (m) 
4050000 
4055000 
4060000 
4065000 
4070000 
4075000 
4080000 
4085000 
4090000 
UTM Northing (m) 
Source: Arnold et al. 2003 (DIRS 164473). 
NOTES: Temperatures are in C. UTM = Universal Transverse Mercator 
Figure 7-13. Simulated Temperatures at the Water Table for the Coupled Thermal Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-53 November 2004 
20 30 40 50 60 70 
Simulated Temperature (C) 
20 
30 
40 
50 
60 
70 
Observed Temperature (C) 
Source: Arnold et al. 2003 (DIRS 164473). 
NOTE: Temperatures are in C. 
Figure 7-14. Simulated Temperatures vs. Observed Temperatures for the Coupled Thermal Model 
7.2.4.2.2 Results and Discussion 
The calibrated SZ site-scale thermal conduction model provides a relatively accurate, unbiased 
match to the observed temperatures in wells in the Yucca Mountain area. The approximately 
normal statistical distribution of residuals in simulated temperature indicates that errors in the 
model are essentially random and not reflective of any systematic misrepresentation of the 
thermal transport processes in the SZ. 
Thermal transport in the SZ is dominated by conductive, predominantly vertical, geothermal heat 
flow at the scale of the SZ site-scale flow model domain. The results of the calibration of the 
conduction-only model indicates that at least 80 percent of the variability in the observed 
temperatures can be explained by thermal conduction, based on the coefficient of determination 
from observed versus simulated temperatures. 
The results of the coupled thermal transport model show that this jointly uncalibrated model is 
unbiased, but less accurate than the heat conduction-only model. The pattern of residuals in 
simulated temperatures suggests that the groundwater flow model overestimates upward 
groundwater flow in the region to the east and southeast of Yucca Mountain and in one area of 
Crater Flat, leading to larger positive residuals. The groundwater flow model also apparently 
overestimates downward groundwater flow to the north of Yucca Mountain and the large 
hydraulic gradient, resulting in larger negative residuals in this area. The results of the coupled 
thermal modeling provide additional confidence in the SZ site-scale flow model in a general 
sense.
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-54 November 2004 
Source: Arnold et al. 2003 (DIRS 164473). 
NOTES: Temperatures are in C. UTM = Universal Transverse Mercator 
Figure 7-15. Residuals in Simulated Temperature at the Water Table for the Coupled Thermal Model 
In the technical work plan governing this modeling task, a criterion was established for the 
independent validation of the SZ site-scale flow model with the ambient temperature data 
(BSC 2004 [DIRS 171421]). This criterion stated that the coupled model would constitute an 
independent validation of the flow model if the simulated temperatures were within 10C of the 
measured temperatures. The uncalibrated coupled thermal transport model of the SZ does meet 
this criterion (85 of the 94 simulated temperatures are within 10C of the measured 
temperatures). Thus, the validation criteria are generally met. The SZ site-scale flow model 
overestimates the upward vertical flow of groundwater in the area to the east and southeast of 
Yucca Mountain, and this flow could be controlled by reducing the vertical permeability in this 
area. The anomalously high, simulated temperatures in a small area of Crater Flat in the coupled 
model are apparently the result of an unrealistic discontinuity in the HFM that strongly focuses 
groundwater flow upward in this region. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 7-55 November 2004 
7.3 VALIDATION SUMMARY 
The SZ site-scale flow model has met the validation criteria established for the validation 
activities completed to date. A comparison of the predicted and recently obtained water levels 
from the newly installed Nye County EWDP wells demonstrates that the SZ site-scale flow 
model can reliably predict the water levels and gradients along the flow path from the repository. 
An analysis of the impact of the differences between observed and predicted hydraulic gradients 
on the specific discharge along the flow path from the repository has identified only a minimal 
impact on the specific discharge, which easily meets the validation criteria previously established 
for this comparison. 
A comparison of the permeability measurements from the ATC with the calibrated permeability 
value for the alluvium has similarly indicated close agreement between calibrated and measured 
values. An analysis of the impact of differences between calibrated and measured permeability 
on the specific discharge along the flow path from the repository also has demonstrated only a 
minimal impact on the specific discharge, which easily meets the validation criteria previously 
established for this comparison. An analysis of the combined impact on the specific discharge of 
the difference between observed and predicted hydraulic gradients and permeability values in the 
area of the ATC have similarly indicated minimal impact that easily meets the validation criteria 
previously established for this comparison. 
The comparison between the flow paths predicted by the SZ site-scale flow model and those 
indicated by hydrochemical analysis has demonstrated close agreement between these flow 
paths, with the flow paths derived from hydrochemical analysis generally enveloping those 
predicted by the SZ site-scale flow model. The thermal model developed from the SZ site-scale 
flow model is capable of modeling thermal transport in the SZ reasonably well, and comparisons 
of the predicted with the observed temperatures generally meet the validation criteria previously 
established for the thermal modeling. The successful meeting of the validation criteria required 
for a Level II model validation provides the appropriate level of confidence required for the use 
of the SZ site-scale flow model in the overall total system performance assessment of the 
repository system. 
The SZ site-scale flow model has been validated by applying acceptance criteria based on an 
evaluation of the models relative importance to the potential performance of the repository 
system. Activities for confidence building during model development have been satisfied 
(Section 7.1.1). Also, all postdevelopment validation requirements defined in the technical work 
plan (BSC 2004 [DIRS 171421], Section 2.2.2) have been fulfilled (with justification for changes 
in the validation criteria), including corroboration of model results with hydrochemical data, 
temperature data, and waterlevel data that were not used in the model development 
(Sections 7.2.1, 7.2.3, and 7.2.4). The model development activities and the postdevelopment 
validation activities described the scientific basis for the SZ site-scale flow model. No future 
activities need to be accomplished for model validation. The model validation activities have 
determined that the SZ site-scale flow model is adequate and sufficiently accurate for the stated 
and intended purpose. 

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INTENTIONALLY LEFT BLANK 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-1 November 2004 
8. CONCLUSIONS 
The SZ site-scale flow model is the culmination of enormous efforts incorporating volumes of 
geologic, hydrologic-testing, and geochemistry data into a coherent representation of flow 
through the SZ near Yucca Mountain. This model is based upon a three-dimensional finite 
element mesh with 500 m  500 m horizontal elements, which grid convergence studies have 
shown to represent the hydrogeologic framework adequately without introducing significant 
numerical error. Additionally, the models vertical resolution varies from 10 to 500 m; the 
higher resolution is near the water table in the area under Yucca Mountain. This model is 
calibrated to and faithfully reproduces two important data sets: the observed potentiometric 
surface (waterlevel data) and boundary fluxes obtained from the SZ regional-scale flow model. 
In addition, the SZ site-scale flow model matches other data quantitatively and qualitatively. 
These data include permeability values derived from single-well and multiple-well tests, 
hydrochemical data, temperature data, and specific-discharge values estimated by the expert 
elicitation panel (CRWMS M&O 1998 [DIRS 100353], Section 3.2). 
The SZ site-scale flow model matches much of the existing SZ-related data, particularly with 
respect to the inferred fluid pathways below the repository area. Although the model is meant to 
represent the SZ accurately, when parameter uncertainty could not be further resolved, parameter 
values were selected to err on the side of conservatism. The hydrochemical data were used as a 
quality check for path-line direction. The SZ model produced path lines from the repository area 
that agree with those inferred from geochemical information. However, there was a bias in the 
calibration, notably in the low-gradient area where the calibrated heads were consistently 34 m 
higher than the observations. 
When using the SZ site-scale flow model for TSPA calculations, three limitations must be noted: 
 Changes to calibration parameter values. Some calibration parameters can be varied 
over a moderate range, and the overall calibration is not adversely affected. For 
example, calibration was performed assuming isotropic horizontal permeabilities, while 
the PA model runs incorporate a range of anisotropic permeabilities. Incorporating 
anisotropy improved calibration. 
 Usable path-line distances. The continuum approach used for the SZ site-scale flow 
model requires large grid blocks that effectively average fracture and rock matrix 
properties. To produce meaningful results, the flow path should be long compared to the 
grid block size. Because the grid block size is 500 m, a minimum distance of 2 km is 
recommended for path lines used in PA calculations. 
 Overall model recharge fluxes. Because the SZ site-scale flow model is linear, recharge 
fluxes may be changed to reflect uncertainty in specific discharge, so long as the 
boundary fluxes and permeabilities are changed proportionally. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-2 November 2004 
8.1 SUMMARY OF MODELING ACTIVITIES 
The SZ site-scale flow model was developed in several stages. First, the hydrogeology of a 
region around Yucca Mountain was numerically characterized with the Death Valley regional 
flow system model (SZ regional-scale model). Second, a detailed conceptual model of flow 
processes was developed for a smaller region (i.e., the site-scale) appropriate for TSPA-LA 
calculations. Third, a numerical model of groundwater flow was developed and calibrated 
(i.e., the SZ site-scale flow model). Fourth, a series of validation activities were completed to 
provide confidence in the SZ site-scale flow model and its output. Finally, results of this model 
were provided and the associated uncertainties were discussed (required before the start of 
TSPA-LA calculations). 
8.1.1 Saturated Zone Flow Characterization 
Much information is available about the regional-scale hydrogeology at Yucca Mountain, both 
from site characterization activities as well as from numerous additional hydrogeologic studies 
that have been conducted at the NTS. Specifically, sufficient information is available to describe 
the stratigraphy, structure, and hydraulic properties of component media, recharge and discharge 
regions, and groundwater flow paths. 
The climate in the Yucca Mountain area is arid, and the water table varies from hundreds of 
meters below ground surface in the northern part of the model to tens of meters below ground 
surface in the southern part of the model. Natural recharge to the SZ is from precipitation 
percolating through the unsaturated zone. Recharge occurs primarily in mountainous areas 
where there is more snow and rainfall (i.e., Yucca Mountain, including regions of higher 
elevation to the north and northeast, and the Spring Mountains 31 miles (50 km) southeast of 
Yucca Mountain). Estimates of recharge rates at the regional scale are based on empirical 
relationships, and the SZ regional-scale model ensures equal SZ recharge and discharge. Flow 
paths in the SZ are well characterized at the regional scale, because numerous waterlevel 
measurements are available. 
The fluxes from the SZ regional-scale flow model were used as targets, because this model 
represents a comprehensive water balance of the Death Valley hydrologic system with fluxes 
constrained by data from spring flows and infiltration rates. Boundary fluxes can help link the 
SZ site-scale flow model to other global-water-balance data, if necessary. The SZ site-scale flow 
model reasonably matched the flux data from the SZ regional scale flow model. 
In the area near Yucca Mountain, waterlevel measurements, hydraulic testing in wells and 
geochemical analyses provide additional information about groundwater flow in the SZ. 
Water-level measurements indicate considerable differences in the magnitude of the hydraulic 
gradient between areas to the north (large hydraulic gradient), west (moderate hydraulic 
gradient), and southeast (low hydraulic gradient) of Yucca Mountain. The hydraulic gradient 
drives flow from the repository to the south and southeast. A vertical, upward hydraulic gradient 
from the underlying carbonate aquifer and the deeper volcanic units is also observed 
immediately downgradient of Yucca Mountain. Data on groundwater chemistry indicate 
significant spatial variability in geochemical and isotopic composition that results from 
differences in flow paths, recharge locations, and groundwater age. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-3 November 2004 
Because the performance of the Yucca Mountain repository is evaluated over a long period, the 
possible impacts of a future wetter climate must be considered. The general locations of areas of 
recharge and discharge depend primarily on the topography of the land surface. Modeling 
studies suggest that increased recharge would result in a higher water table and steeper hydraulic 
gradients. Field mapping of the occurrence of zeolites and paleospring deposits has confirmed 
that a higher water table existed during past wetter climates and supports numerical simulations 
of the possible impacts of climate change. Consequently, wetter climates in the future are 
expected to result in faster groundwater flow rates along present-day flow paths. The impacts of 
increased water table are discussed in the SZ transport model report (BSC 2004 [DIRS 170036], 
Section 6.6 and Appendix E1). 
As groundwater in the Death Valley system moves from recharge to discharge areas, flow rates 
and paths depend largely on the hydraulic properties of the media along the flow paths. 
Geologic studies have identified the important rock types and their spatial distribution. The rock 
types that play the largest role in regional hydrogeology are Paleozoic carbonates, 
Quaternary-Tertiary volcanic rocks, and Quaternary-Tertiary sediments and volcanic tuffs that 
fill structural depressions (referred to as valley-fill material in portions of this report). Relatively 
shallow flow occurs in the volcanic rocks and valley fill (primarily alluvium), and deeper flow 
occurs in the regionally extensive carbonate aquifer. Along the inferred shallow flow path, 
groundwater flow paths originate in volcanic rocks near the repository site and continue into 
younger valley-fill deposits at greater distances. 
The permeability of the volcanic rocks near Yucca Mountain is increased by the presence of 
fractures. An extensive suite of field observations, interpretations of borehole logs, boreholes 
hydrologic tests, lab-scale tests, and field tracer tests (C-wells complex) confirm that fractures 
dominate groundwater flow in the volcanic rocks. However, flow in the alluvium occurs through 
the primary porosity of these sediments. 
8.1.2 Conceptual Model of SZ Site-Scale Flow 
The SZ site-scale conceptual model is a synthesis of what is known about flow processes at the 
scale required for TSPA-LA calculations. This knowledge builds upon, and is consistent with, 
information that has accumulated at the regional scale, but it is more detailed because a higher 
density of data is available at the site-scale. 
Information from geologic maps and cross sections, borehole data, fault-trace maps, and 
geophysical data were used to construct the HFM, a three-dimensional interpretation of the 
hydrostratigraphy and geologic structure of the SZ site-scale flow model. Rock stratigraphies 
within the framework model are grouped into 18 hydrogeologic units that are classified as having 
either relatively large permeability (aquifers) or relatively small permeability (confining units). 
The framework model specifies the position and geometry of these hydrogeologic units. In 
addition, the framework model identifies major faults that affect groundwater flow. 
The source of most of the groundwater flow in the SZ site-scale flow model is lateral flow 
through the western, northern, and eastern boundaries. A small portion (approximately 
5 percent) of the total flux through the SZ site-scale flow model is from precipitation and surface 
runoff infiltrating along Fortymile Wash. Outflow from the site-scale region is chiefly through 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-4 November 2004 
the southern boundary. A small amount of water is removed by pumping wells located in the 
Amargosa Valley near the southern boundary of the model domain. As groundwater moves 
away from the repository, it first flows through a series of welded and nonwelded volcanic tuffs. 
These flow paths pass into alluvium. 
8.1.3 Mathematical Model and Numerical Approach 
The mathematical basis (and associated numerical approaches) of the SZ site-scale flow model is 
designed to assist in quantifying the uncertainty in the permeability of rocks in the geologic 
framework model and to represent accurately all included flow process. An automated 
parameter estimation approach is used to obtain the distribution of rock permeabilities yielding 
hydraulic heads that best matched measured values, as well as lateral-flow rates across model 
boundaries that are compatible with results from the SZ regional-scale flow model. 
Calculations of groundwater flow (specific-discharge field) are made under steady-state 
assumptions. The approach of not explicitly representing fractures in the volcanic rocks is 
reasonable at the scale required for the TSPA-LA (tens of kilometers) but is not accurate at 
length scales shorter than the dimensions of model grid blocks (less than 500 m). 
8.1.4 Model Validation and Confidence Building 
Confidence in the results of the mathematical model was built by comparing: (1) calculated to 
observed hydraulic heads; (2) predicted to measured permeabilities and therefore specific 
discharge; and (3) predicted and measured groundwater temperatures. In addition, it was 
confirmed that the flow paths leaving the region of the repository are consistent with those 
inferred both from gradients of measured head and from independent water-chemistry data. 
8.2 OUTPUTS 
The technical output from this model comprises the SZ site-scale flow model and associated 
input and output files (base case flow files). Output from the SZ site-scale flow model consists 
of the flow fields for the site-scale area that will be integrated into the SZ transport model and 
used to generate radionuclide breakthrough curves. Specifically, the output from the SZ 
site-scale flow model contains the specific discharge and the flow paths from the water table 
beneath the repository horizon to the accessible environment. 
The computer files associated with the SZ site-scale flow model are contained in SZ Flow and 
Transport Model, Hydrogeologic Surface Files (output DTN: LA0304TM831231.001) and SZ 
Site-Scale Flow Model, FEHM Files for Base Case (DTN: LA0304TM831231.002 
[DIRS 163788]). 
8.3 OUTPUT UNCERTAINTY 
This section describes remaining uncertainties with the two technical outputs of this model 
report: specific discharge and flow paths. The section also recommends how the uncertainty 
associated with the outputs should be considered. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-5 November 2004 
8.3.1 Specific Discharge Uncertainty Range 
In previous SZ site-scale flow models for PA calculations, the specific discharge was varied 
from one-tenth of its nominal value to 10 times its nominal value. Since the uncertainty in 
permeability directly translates into the uncertainty in specific discharge, assuming a constant 
head gradient, experience gained in investigating permeability values during calibration is 
applicable to specific discharge. Based on recent calibration experience and the evaluation of 
permeability data from Yucca Mountain and other sites, this range may extend from one-third of 
its nominal value to three times the nominal value. The nominal value was obtained from the 
calibration effort described in this model report. Because the model is linear, calibration is 
preserved by scaling the fluxes, recharge, and permeabilities proportionally. It should also be 
noted that this scaling does not cause any permeabilities to exceed the limits imposed in the 
calibration process for any hydrogeologic unit along the flow path. In the discussion below, the 
focus is on the Bullfrog tuff unit because calibration experience has shown that, for all 
reasonable scenarios, the fluid particles leaving the repository area travel primarily through this 
unit before entering the alluvial aquifer. 
From the re-evaluation of the permeability data described above and the statistical summary of 
the permeability data given in Table 6-24, three important facts emerge. First, the upper 
95 percent confidence interval for the mean permeability of the Bullfrog tuff from the cross-hole 
tests (3.4  1011 m2) is approximately three times the mean value (1.1  1011 m2). The mean 
value, in turn, is very close to the nominal calibration value of 1.5  1011 m2 obtained for the SZ 
site-scale flow model. Second, alternative conceptual models implemented in the numerical 
model since the previous version of this report (BSC 2001 [DIRS 155974]) have resulted in a 
range of estimates for the permeability of the Bullfrog tuff that vary by less than 100 percent of 
the nominal permeability value. Third, the permeability data from Yucca Mountain had a 
practical maximum of 7.6  1011 m2 from individual tests (see Table 6-26) in highly fractured 
intervals in volcanic rock. Although this value exceeds the nominal value by a factor of five, 
uncertainty in the geometric-mean permeability is a more relevant measure of the uncertainty. 
Additionally, the intrinsic model formulation requires homogeneity within an element 
(volume-averaged permeability). Recall that large permeability measurements from the C-wells 
complex were probably due to their proximity to the Midway Valley fault. Overall, these 
arguments support the range of permeabilities being within three times the nominal value. 
Similarly, because the lower 95 percent confidence interval of the geometric-mean permeability 
of the Bullfrog tuff is approximately one-third of the mean value, this ratio is recommended for 
the lower limit in PA calculations. It should be noted that low permeabilities do not negatively 
impact modeled performance at this location. When the SZ site-scale model was run with 
permeabilities of three times and one-third of the nominal value, overall model calibration 
remained within acceptable tolerances. 
In the 18-km compliance region, performance assessment calculations are strongly influenced by 
travel of fluid particles in the alluvial aquifer. Recent aquifer tests in well NC-EWDP-19D 
(Table 7-4) and permeability data for the NTS suggest that the variability of the alluvial aquifer 
permeability is less than that of the volcanic rocks. In particular, three of the four tests produced 
permeability values that were within a factor of 2 of the mean value. Thus, the permeability ratio 
ranges derived from the Bullfrog tuff analysis described above should be sufficient to bound the 
uncertainty in the alluvial aquifer permeability for the 18-km compliance calculations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-6 November 2004 
8.3.2 Flow Paths Uncertainty 
The flow paths from the water table beneath the repository to the accessible environment directly 
affect breakthrough curves and associated radionuclide transport times. Because the flow paths 
are close to the water table and transition from the volcanic tuffs to the alluvium, flow-path 
uncertainty directly affects the length of flow in the volcanic tuffs and in the alluvium. 
Uncertainty in flow paths is affected by anisotropy in hydraulic properties of the volcanic tuffs. 
Large-scale anisotropy and heterogeneity were implemented in the SZ site-scale flow model 
through direct incorporation of known hydraulic features, faults, and fractures. Small-scale 
anisotropy was derived from analysis of hydraulic testing at the C-wells (BSC 2004 
[DIRS 170010], Section 6.2.6). This scientific analysis report also recommends an uncertainty 
range in anisotropy that should be used in the SZ site-scale flow model to account for uncertainty 
in the flow paths. For isotropic permeability, flow-path length is approximately 24.5 km. For 
anisotropy ratios of 20 and 0.05, flow path lengths are 22 and 27 km, respectively. This is an 
acceptable range of variability in model results. 
The alternate model developed to assess the impact of new data and analyses made available 
since the development of the SZ site-scale flow model indicates a straight north-to-south flow 
path. These alternate flow paths were incorporated in transport simulations (BSC 2004 
[DIRS 170036]) to assess their effect on radionuclide transport. 
The model is adequate for its intended use of providing flow field predictions as input to the SZ 
site-scale transport model necessary to generate radionuclide breakthrough curves. 
8.4 HOW THE APPLICABLE ACCEPTANCE CRITERIA ARE ADDRESSED 
This section describes how the acceptance criteria in the YMRP (NRC 2003 [DIRS 163274], 
Section 2.2.1.3.8.3, Flow Paths in the Saturated Zone, are addressed by this report. 
Acceptance Criteria from Section 2.2.1.3.8.3, Flow Paths in the Saturated Zone 
Acceptance Criterion 1: System Description and Model Integration Are Adequate. 
Subcriterion (1): Section 1 explains that this model generates SZ velocity fields which are used 
as inputs for the model of transport in the SZ and are abstracted in the TSPA. The important 
physical phenomena are adequately incorporated in the SZ abstraction process as described in 
the following subsections: hydraulic gradients (Section 6.3.2.4); vertical gradients 
(Section 6.3.2.5); lateral boundary conditions (Section 6.3.2.6); Recharge (Section 6.3.2.7); 
Discharge (Section 6.3.2.8); heterogeneity (Section 6.3.2.9); faults (Section 6.3.2.10); and 
groundwater flow processes (Section 6.3.3.). The discussion of groundwater table rise in 
Section 6.4.5.1 uses consistent and appropriate assumptions about climate change. 
Subcriterion (2): Aspects of hydrology, geology and geochemistry that may affect flow paths in 
the SZ are described adequately in Section 6.3 and Appendix A. 
Subcriterion (4): Section 4.1 states that: (1) the SZ flow model uses the same recharges as used 
in the 1997 DVRFS model in the area represented by the site scale model; (2) the lateral 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-7 November 2004 
boundary fluxes from the DVRFS are used to calibrate the site-scale flow model; and (3) the 
fluxes from the DVRFS were averaged and used as calibration targets for the SZ site-scale 
model. The SZ site-scale flow model uses appropriate recharge values from flow in the 
unsaturated zone. 
Subcriterion (5): Section 6.2 provides sufficient data and technical bases to assess the degree to 
which FEPs have been included in the flow paths. 
Subcriterion (6): Flow paths in the SZ are adequately delineated, considering site conditions, as 
described in Section 6.6.2.3 and Appendix A. Section 6.8 shows how the flow model that was 
developed generates flow fields that simulate radionuclide transport in saturated porous rock and 
alluvium under natural and forced gradient conditions. 
Subcriterion (7): The effect of climate on flow paths is evaluated adequately in Section 6.4.5.1. 
Subcriterion (8): Section 6.5.3.7 explains how the linear approximation of the temperature 
gradient captures the effect of geothermal heat flux on groundwater viscosity. 
Subcriterion (9): The impact of the expected water table rise on potentiometric heads and flow 
directions, and consequently on repository performance, is adequately considered in 
Section 6.4.5.1. 
Subcriterion (10): This report was prepared in accordance with the Quality Assurance 
Requirements and Description (QARD) (DOE 2004 [DIRS 171539]), which commits to this 
U.S. Nuclear Regulatory Commission guidance. Compliance with the QARD was determined 
through multiple reviews. 
Acceptance Criterion 2: Data Are Sufficient for Model Justification. 
Subcriterion (1): Section 4.1 identifies the geological, hydrological, and geochemical values 
used in this model to evaluate flow paths in the SZ and adequately justifies those values by 
identifying their reliable sources. Section 6.5.3 adequately describes how the data were used, 
interpreted, and appropriately synthesized into parameters by explaining how water level and 
head distributions, definitions of the hydrogeologic units, the distribution of recharge flux and 
lateral fluxes into the model domain, feature and fault distribution, temperature profiles in wells, 
and boundary conditions were incorporated into the site-scale model for SZ flow. 
Section 6.5.3.1 describes the development of the hydrogeologic framework, which, with the 
known features of the site is used to design a grid for flow modeling. Section 6.5.3.2 describes 
the generation of the grid, which enables the data to be assigned to hydrogeologic units and 
features, recharge fluxes, hydrogeologic properties, and boundary conditions at node points. 
Section 6.5.3.3 describes the use of hydrogeologic properties, Section 6.5.3.4 describes the 
representation of features, Section 6.5.3.5 describes the use of the boundary conditions described 
in Section 6.3.2.6, Section 6.5.3.6 describes recharge, and Section 6.5.3.7 describes how the 
hydrogeologic properties are specified for each node in the computational grid. Section 7.2.4 
describes the permeability data obtained at the NTS, including the lower carbonate aquifer 
(Section 7.2.4.1), the valley fill aquifer (Section 7.2.4.2), the welded tuff aquifer 
(Section 7.2.4.3), and the lava flow aquifer (Section 7.2.4.4). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-8 November 2004 
Subcriterion (2): The sufficiency of the data collected on the natural system to establish 
boundary conditions on flow paths in the SZ is demonstrated in Section 6.3.2. Section 6.3.2 
describes the hydrogeologic setting of the SZ flow system near Yucca Mountain. Section 6.3.2.1 
relates the geologic features to flow in the SZ. Section 6.3.2.2 describes the HFM that includes 
faults, zones of hydrothermal alteration, and other features that affect flow in the SZ. 
Section 6.3.2.3 uses the potentiometric surface map to determine the general direction of 
groundwater flow. Section 6.3.2.4 describes the hydraulic gradients and Section 6.3.2.5 
describes the vertical gradients. Section 6.3.2.6 explains how the boundary conditions are 
derived from regional water level and head data form fixed-head boundary conditions on the 
lateral sides of the model. Section 6.3.2.7 describes the three components of recharge and 
Section 6.3.2.8 reports that no natural discharge is observed. Section 6.3.2.9 describes the 
observed physical and chemical heterogeneity of the rocks and water in the SZ. Section 6.3.2.10 
describes the role of faults. Initial conditions are not included in the model because it is a 
steady-state model. 
Subcriterion (3): The appropriateness of the techniques used to obtain the SZ geologic, 
hydrologic, and geochemical data used in this model is established in the reliable sources of this 
data listed in Section 4.1. Adequacy of the data is illustrated by the observation that the model 
did not change when updated with additional waterlevel data from new wells (Section 4.1). 
Section 7.2.3 describes the acquisition of data about permeability from single-hole tests 
(Section 7.2.3.1) and cross-hole tests (Section 7.2.3.2). 
Subcriterion (4): Section 6.5 provides sufficient information to substantiate that the proposed 
mathematical groundwater modeling approach and proposed model is applicable to site 
conditions. Section 6.5.1 discusses the equations from the basic laws of flow that were applied 
and Section 6.5.2 describes the computational model used to solve those equations. 
Section 6.5.3 describes the inputs from data about the site, including the HFM (Section 6.5.3.1), 
grid generation (Section 6.5.3.2), hydrogeologic properties (Section 6.5.5.3), discrete features 
and regions (Section 6.5.3.4), boundary conditions (Section 6.5.3.5), and recharge 
(Section 6.5.3.6). 
Section 6.61 provides sufficient information to substantiate that the proposed mathematical 
groundwater model is calibrated. Section 6.6.1.1 describes the calibration criteria, 
Section 6.6.1.2 describes the parameter optimization procedure, Section 6.6.1.3 describes the 
calibration targets, and Section 6.6.1.4 describes the calibration parameters. Section 6.6.2 
describes the calibration results for water levels (Section 6.6.2.1), fluxes (Section 6.6.2.2), flow 
paths (Section 6.6.2.3), and specific discharge (Section 6.62.4). 
Acceptance Criterion 3: Data Uncertainty Is Characterized and Propagated Through the 
Model Abstraction. 
Subcriterion (1): Section 6.6.1 explains how calibration is used to optimize the values of 
important model parameters in a way that is technically defensible, reasonably accounts for 
uncertainties and variabilities, and does not result in an under-representation of the risk estimate. 
Subcriterion (2): The effect of climate on flow paths is evaluated adequately in Section 6.4.5.1. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-9 November 2004 
Subcriterion (3): Section 6.6.1 and 6.8 show how uncertainty has been adequately represented 
in the development of parameters for the model. 
Subcriterion (4): A SZ flow expert elicitation panel was conducted in accordance with Kotra et 
al. (1996 [DIRS 100909] and addressed the following issues: 
 Appropriateness of the horizontal to vertical anisotropy ratio of 10:1 (Section 5) 
 Estimates of discharge from the volcanic aquifer (Section 6.3.3) 
 Semiperched water as a reason for the observed large hydraulic gradient 
(Section 6.5.3.4) 
 Specific discharge near Yucca Mountain (Sections 6.6.1.2, 6.6.2.4, and 8). 
Acceptance Criterion 4: Model Uncertainty Is Characterized and Propagated Through the 
Model Abstraction. 
Subcriterion (1): Several ACM, which are consistent with available data and current scientific 
understanding, are identified in Section 6.4. They are: (1) models for the LHG north of Yucca 
Mountain (Section 6.4.1); (2) a shallow representation of the Solitario Canyon fault 
(Section 6.4.2); (3) anisotropies in hydraulic properties, with and without vertical anisotropy 
(Section 6.4.31), and constant and variable horizontal anisotropy ratios (Section 6.4.3.2); (4) four 
versions of the potentiometric surface of the uppermost part of the SZ (Section 6.4.4); (5) water 
table rise resulting from climate change (Section 6.4.5); and (6) the alternate model developed to 
assess the impact of new data and of the analyses which were made available for the SZ 
site-scale flow model. 
Section 6.7 describes two ACMs in detail, the LHG and a Shallow Solitario Canyon fault. 
Section 6.7.1 discuss the LHG ACM, which accounts for the observed large hydraulic gradient, 
which is an observed feature of the flow system near Yucca Mountain. Section 6.7.1.1 provides 
an overview of this ACM. Three versions of the LHG ACM are discussed in Section 6.7.1.2: 
(1) ANF, (2) AFW, and (3) AWF plus the AWF/GDF. Water level and flow path results and 
limitations of the ACMs for the flow fields considered in the TSPA are discussed in 
Section 6.7.1.3. The assessment in Section 6.7.1.4 shows that this alternative conceptualization 
of the LHG has little effect on the site-scale flow results, so that the base case provides an 
adequate model. 
Section 6.7.2 discusses the Solitario Canyon fault ACM, which simulates an alternative 
extension of the fault from the water table to the top of the carbonate aquifer. Section 6.7.2.1 
provides an overview of this Shallow fault. A comparison of the heads and flow paths is 
presented in Section 6.7.2.3, where differences from the base case are identified. The subsystem 
analysis in Section 6.7.2.4 shows that this ACM representation of the Solitario Canyon fault does 
not differ substantially from performance of the base case. 
The results and limitations of the ACMs were appropriately considered in the abstractions. As 
discussed in Sections 6.4 and 6.7, the LHG ACM and Solitario fault ACM did not significantly 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-10 November 2004 
affect model results, and, so were not included in the abstractions. Vertical anisotropy was not 
included (Sections 6.4.3.1 and 6.8.3.2). This is because the vertical anisotropy from an expert 
elicitation is only a rule of thumb and removal of the vertical anisotropy from model calibration 
did not significantly affect the difference between the measured and computed heads 
(Section 6.8.3.1). Horizontal anisotropy was included in the TSPA analysis (Section 6.4.3.2). 
Of the four versions of the potentiometric surface map discussed in Section 6.4.4.1-6.4.4.4, it 
was determined that the base-case qualitatively reproduces the important features of the 
potentiometric surface (Section 6.4.4.4). Sections 6.4.5.1 and 6.4.5.2 explain how the change in 
SZ flow paths resulting from a rise in the water table need not be included in the TSPA because 
the use of scaling factors conservatively accounts for the impact of climate changes on SZ flow. 
Subcriterion (2): Conceptual model uncertainties are adequately defined and documented in 
Sections 6.4 and 6.7, as discussed above, and in Section 6.8. These sections also include the 
proper assessment of the effects on conclusions regarding performance. Section 6.8.1 addresses 
uncertainty in the flow paths due to alternative conceptualizations of the LHG, and 
Section 6.8.2 discusses the related issue of perched water. 
Section 6.7.1.3 discusses the effects of the three LHG ACMs on flow and demonstrates the 
adequacy of the base case model for repository performance. The Solitario Canyon fault ACM 
addresses uncertainty in the depth of the fault. See, Section 6.7.2.1. Section 6.7.2.3 describes 
the investigations into the importance of the depth of the fault and Section 6.7.2.4 concludes that 
the alternative depth would not affect repository performance. 
Section 6.8.3.1 shows that variations in vertical anisotropy do not substantially affect repository 
performance. Section 6.8.3.2 explains that variations in horizontal anisotropy are within the 
uncertainty ranges used in the TSPA-SR. This uncertainty is propagated forward to the 
TSPA-LA. 
Section 6.8.4 explains why the use of volume-averaged representations of faults by zones of 
enhanced permeability provide adequate representations of fault flow properties. 
Uncertainty in the quantification of specific discharge is discussed in Sections 6.8.5 and 
6.8.5.2 and is shown that for the volcanic aquifer and the alluvial aquifer along the flow path, 
there is general consistency between the specific discharge simulated by the model and the 
median of values of uncertainty ranges estimated by the SZ expert panel from testing data. 
Accordingly, an uncertainty distribution for specific discharge has been constructed as described 
in Section 6.8.5. This uncertainty is propagated forward to the TSPA-LA. 
Uncertainty in the hydrologic contacts is discussed in Section 6.8.5.1 and shown to have 
moderate effects in some cases. Accordingly, this uncertainty was determined not to warrant 
propagation to the TSPA-LA. 
Uncertainty due to scaling is discussed in Section 6.8.6, where it is concluded that such 
uncertainty does not significantly affect flow modeling. 
Subcriterion (3): The conceptual model uncertainty considered in this report is consistent with 
available site characterization data and field measurements. Section 6.8.1 describes the model 
uncertainty associated with the LHG. Sections 6.7.1.1 and 6.7.1.2 describe how the observed 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-11 November 2004 
LHG is approximated by alternative conceptualizations based on changes in permeability instead 
of on low permeability east-west feature that has been incorporated in the base-case conceptual 
model but has not been observed. Section 6.7.1.4 explains why the ACMs are not considered to 
significantly affect hydrologic conditions. Section 6.7.2.1 discusses the relation between field 
measurements and the treatment of uncertainty in the depth of the Solitario Canyon fault and 
shows that flow paths from the water table underneath the repository to the accessible 
environment are unchanged. Accordingly, the uncertainty does not result in an under-estimate of 
the risk. 
Section 6.8.2 explains why perched water was not included in the SZ site-scale flow model. 
Section 6.8.3 address vertical and horizontal anisotropy that can affect flow path, flow direction, 
and specific discharge. Sections 6.8.3.1 and 6.8.3.2 discuss the vertical and horizontal 
anisotropies, respectively. Section 6.8.4 explains why the uncertainty associated with the 
representation of faults by grid blocks having enhanced permeability is acceptable. Section 6.8.5 
addresses uncertainty in the quantification of groundwater specific discharge. Section 6.8.5.1 
addresses the effects of uncertainty in the hydrogeologic contact on specific discharge. 
Section 6.8.6 addresses uncertainty due to scaling. Section 6.8.5.2 addresses the uncertainty 
range for specific discharge. Section 6.8.5.3 addresses the uncertainty related to assuming flow 
in a porous continuum instead of through faults. These sections also explain how these 
uncertainties have been addressed so as not to result in an under-representation of the risk. 
Subcriterion (4): Alternative modeling approaches are appropriate and consistent with available 
data and current scientific knowledge, and appropriately consider their results and limitations, 
using analyses that are sensitive to the processes modeled, as discussed above. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 8-12 November 2004 
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Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-1 November 2004 
9. INPUTS AND REFERENCES 
The following is a list of the references cited in this document. Column 2 represents the unique 
six-digit numerical identifiers (the Document Input Reference System numbers), which are 
placed in the text following the reference callout (e.g., BSC 2004 [DIRS 109715]). The purpose 
of these numbers is to assist in locating a specific reference. Multiple sources by the same author 
(e.g., BSC 2004) are sorted alphabetically by title. 
9.1 DOCUMENTS CITED 
Ahlers, C.F.; Finsterle, S.; and Bodvarsson, G.S. 1999. Characterization and 
Prediction of Subsurface Pneumatic Response at Yucca Mountain, Nevada. 
Journal of Contaminant Hydrology, 38, (1-3), 47-68. New York, New York: 
Elsevier. TIC: 244160. 
109715 
Arnold, B.W.; Zyvoloski, G.; Economy, K.; and Wallace, M. 2003. Thermal 
Transport in the Saturated Zone Site-Scale Model at Yucca Mountain. 
Proceedings of the 10th International High-Level Radioactive Waste Management 
Conference (IHLRWM), March 30-April 2, 2003, Las Vegas, Nevada. Pages 
301-306. La Grange Park, Illinois: American Nuclear Society. TIC: 254559. 
164473 
Benson, L. and Klieforth, H. 1989. Stable Isotopes in Precipitation and Ground 
Water in the Yucca Mountain Region, Southern Nevada: Paleoclimatic 
Implications. Aspects of Climate Variability in the Pacific and the Western 
Americas. Peterson, D.H., ed. Geophysical Monograph 55. Pages 41-59. 
Washington, D.C.: American Geophysical Union. TIC: 224413. 
104370 
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. 
101036 
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. 
101194 
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. 
101195 
Blankennagel, R.K. and Weir, J.E., Jr. 1973. Geohydrology of the Eastern Part of 
Pahute Mesa, Nevada Test Site, Nye County, Nevada. Professional Paper 712-B. 
Washington, D.C.: U.S. Geological Survey. TIC: 219642. 
101233 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-2 November 2004 
Bower, K.M.; Gable, C.W.; and Zyvoloski, G.A. 2000. Effect of Grid Resolution 
on Control Volume Finite Element Groundwater Modeling of Realistic Geology. 
LA-UR-001870. Los Alamos, New Mexico: Los Alamos National Laboratory. 
TIC: 248256. 
149161 
Brodsky, N.S.; Riggins, M.; Connolly, J.; and Ricci, P. 1997. Thermal Expansion, 
Thermal Conductivity, and Heat Capacity Measurements for Boreholes UE25 
NRG-4, UE25 NRG-5, USW NRG-6, and USW NRG-7/7A. SAND95-1955. 
Albuquerque, New Mexico: Sandia National Laboratories. 
ACC: MOL.19980311.0316. 
100653 
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. 
102004 
BSC (Bechtel SAIC Company) 2001. Calibration of the Site-Scale Saturated Zone 
Flow Model. MDL-NBS-HS-000011 REV 00 ICN 01. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: MOL.20010713.0049. 
155974 
BSC 2001. Geochemical and Isotopic Constraints on Groundwater Flow 
Directions, Mixing, and Recharge at Yucca Mountain, Nevada. 
ANL-NBS-HS-000021 REV 00 ICN 2. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20020128.0434. 
158606 
BSC 2002. Analysis of Geochemical Data for the Unsaturated Zone. 
ANL-NBS-HS-000017 REV 00 ICN 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20020314.0051. 
160247 
BSC 2003. Repository Design, Repository/PA IED Subsurface Facilities. 
800-IED-EBS0-00401-000-00C. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: ENG.20030303.0002. 
162289 
BSC 2003. Technical Work Plan for: Saturated Zone Flow and Transport 
Modeling and Testing. TWP-NBS-MD-000002 REV 01 ICN 01. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20031203.0002. 
166034 
BSC 2004. Development of Numerical Grids for UZ Flow and Transport 
Modeling. ANL-NBS-HS-000015 REV 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: DOC.20040901.0001. 
169855 
BSC 2004. Engineered Barrier System Features, Events, and Processes. 
ANL-WIS-PA-000002 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20040621.0002. 
170900 
BSC 2004. Features, Events, and Processes in SZ Flow and Transport. 
ANL-NBS-MD-000002, Rev. 03. Las Vegas, Nevada: Bechtel SAIC Company. 
170013 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-3 November 2004 
BSC 2004. Hydrogeologic Framework Model for the Saturated Zone Site Scale 
Flow and Transport Model. MDL-NBS-HS-000024, Rev. 00. Las Vegas, Nevada: 
Bechtel SAIC Company. 
170008 
BSC 2004. Particle Tracking Model and Abstraction of Transport Processes. 
MDL-NBS-HS-000020 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041020.0016. 
170041 
BSC 2004. Probability Distribution for Flowing Interval Spacing. 
ANL-NBS-MD-000003 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20040923.0003. 
170014 
BSC 2004. Q-List. 000-30R-MGR0-00500-000-000 REV 00. Las Vegas, Nevada: 
Bechtel SAIC Company. ACC: ENG.20040721.0007. 
168361 
BSC 2004. Recharge and Lateral Groundwater Flow Boundary Conditions for the 
Saturated Zone Site-Scale Flow and Transport Model. ANL-NBS-MD-000010 
REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041008.0004. 
170015 
BSC 2004. Saturated Zone Flow and Transport Model Abstraction. 
MDL-NBS-HS-000021 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20041028.0003. 
170042 
BSC 2004. Saturated Zone In-Situ Testing. ANL-NBS-HS-000039 REV 01. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041115.0008. 
170010 
BSC 2004. Site-Scale Saturated Zone Transport. MDL-NBS-HS-000010 REV 02. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041103.0004. 
170036 
BSC 2004. Technical Work Plan For: Natural System - Saturated Zone Analysis 
and Model Report Integration. TWP-NBS-MD-000002 REV 02. Las Vegas, 
Nevada: Bechtel SAIC Company. ACC: DOC.20040706.0007. 
170115 
BSC 2004. Technical Work Plan for: Natural System - Saturated Zone Analysis 
and Model Report Integration. TWP-NBS-MD-000002 REV 02 ICN 01. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20040818.0004. 
171421 
BSC 2004. UZ Flow Models and Submodels. MDL-NBS-HS-000006 REV 02. 
Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20041101.0004. 
169861 
BSC 2004. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and 
Transport Model. ANL-NBS-HS-000034 REV 02. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: DOC.20041012.0002. 
170009 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-4 November 2004 
BSC 2004. Yucca Mountain Site Description. TDR-CRW-GS-000001 REV 02 
ICN 01. Two volumes. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20040504.0008. 
169734 
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. 
100106 
Burke, W.H.; Denison, R.E.; Hetherington, E.A.; Koepnick, R.B.; Nelson, H.F.; 
and Otto, J.B. 1982. Variation of Seawater 87Sr/ 86Sr Throughout Phanerozoic 
Time. Geology, 10, 516-519. Boulder, Colorado: Geological Society of 
America. TIC: 255085. 
162906 
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. 
126814 
Canori, G.F. and Leitner, M.M. 2003. Project Requirements Document. 
TER-MGR-MD-000001 REV 02. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20031222.0006. 
166275 
Chapman, J.B. and Lyles, B.F. 1993. Groundwater Chemistry at the Nevada Test 
Site: Data and Preliminary Interpretations. DOE/NV/10845-16. Las Vegas, 
Nevada: U.S. Department of Energy, Nevada Operation Office. 
ACC: MOL.20031023.0087. 
162940 
Cheng, H.; Edwards, R.L.; Hoff, J.; Gallup, C.D.; Richards, D.A.; and Asmerom, 
Y. 2000. The Half-Lives of Uranium-234 and Thorium-230. Chemical Geology, 
169, 17-33. Amsterdam, The Netherlands: Elsevier. TIC: 249205. 
153475 
Chipera, S.J. and Bish, D.L. 1997. Equilibrium Modeling of 
Clinoptilolite-Analcime Equilibria at Yucca Mountain, Nevada. Clays and Clay 
Minerals, 45, (2), 226-239. Long Island City, New York: Pergamon Press. 
TIC: 233948. 
105079 
Chipera, S.J.; Bish, D.L.; and Carlos, B.A. 1995. Equilibrium Modeling of the 
Formation of Zeolites in Fractures at Yucca Mountain, Nevada. Natural Zeolites 
93: Occurrence, Properties, Use, Proceedings of the 4th International Conference 
on the Occurrence, Properties, and Utilization of Natural Zeolites, June 20-28, 
1993, Boise, Idaho. Ming, D.W. and Mumpton, F.A., eds. Pages 565-577. 
Brockport, New York: International Committee on Natural Zeolites. 
TIC: 243086. 
100025 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-5 November 2004 
Claassen, H.C. 1985. Sources and Mechanisms of Recharge for Ground Water in 
the West-Central Amargosa Desert, NevadaA Geochemical Interpretation. U.S. 
Geological Survey Professional Paper 712-F. Washington, D.C.: United States 
Government Printing Office. TIC: 204574. 
101125 
Clark, I.D. and Fritz, P. 1997. Environmental Isotopes in Hydrogeology. 
Boca Raton, Florida: Lewis Publishers. TIC: 233503. 
105738 
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. 
101040 
CRWMS M&O (Civilian Radioactive Waste Management System Management & 
Operating Contractor) 1998. Saturated Zone Flow and Transport Expert 
Elicitation Project. Deliverable SL5X4AM3. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19980825.0008. 
100353 
CRWMS M&O 2000. Calibration of the Site-Scale Saturated Zone Flow Model. 
MDL-NBS-HS-000011 REV 00. Las Vegas, Nevada: CRWMS M&O. 
ACC: MOL.20000825.0122. 
139582 
CRWMS M&O 2000. Input and Results of the Base Case Saturated Zone Flow 
and Transport Model for TSPA. ANL-NBS-HS-000030 REV 00. Las Vegas, 
Nevada: CRWMS M&O. ACC: MOL.20000526.0330. 
139440 
CRWMS M&O 2000. Total System Performance Assessment for the Site 
Recommendation. TDR-WIS-PA-000001 REV 00 ICN 01. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.20001220.0045. 
153246 
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. 
101043 
Czarnecki, J.B. 1985. 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. TIC: 203222. 
160149 
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. 
100377 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-6 November 2004 
DAgnese, 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. 
100131 
DAgnese, F.A.; OBrien, G.M.; Faunt, C.C.; and San Juan, C.A. 1999. Simulated 
Effects of Climate Change on the Death Valley Regional Ground-Water Flow 
System, Nevada and California. Water-Resources Investigations Report 98-4041. 
Denver, Colorado: U.S. Geological Survey. TIC: 243555. 
120425 
DAgnese, F.A.; OBrien, G.M.; Faunt, C.C.; Belcher, W.R.; and San Juan, C. 
2002. A Three-Dimensional Numerical Model of Predevelopment Conditions in the 
Death Valley Regional Ground-Water Flow System, Nevada and California. 
Water-Resources Investigations Report 02-4102. Denver, Colorado: U.S. 
Geological Survey. TIC: 253754. 
158876 
Davisson, M.L.; Kenneally, J.M.; Smith, D.K.; Hudson, G.B.; Nimz, G.J.; and 
Rego, J.H. 1994. Preliminary Report on the Isotope Hydrology Investigations at 
the Nevada Test Site: Hydrologic Resources Management Program, 
FY 1992-1993. UCRL-ID-116122. Livermore, California: Lawrence Livermore 
National Laboratory, Nuclear Chemistry Division. TIC: 210954. 
162939 
Day, W.C.; Dickerson, R.P.; Potter, C.J.; Sweetkind, D.S.; San Juan, C.A.; Drake, 
R.M., II; and Fridrich, C.J. 1998. Bedrock Geologic Map of the Yucca Mountain 
Area, Nye County, Nevada. Geologic Investigations Series I-2627. Denver, 
Colorado: U.S. Geological Survey. ACC: MOL.19981014.0301. 
100027 
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. Miscellaneous Investigations Series Map I-2601. Washington, 
D.C.: U.S. Geological Survey. ACC: MOL.19980611.0339. 
101557 
de Marsily, G. 1986. Quantitative Hydrogeology: Groundwater Hydrology for 
Engineers. San Diego, California: Academic Press. TIC: 208450. 
100439 
Dettinger, M.D. 1989. Reconnaissance Estimates of Natural Recharge to Desert 
Basins in Nevada, U.S.A., by Using Chloride-Balance Calculations. Journal of 
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Tompson, A.F.B. and Gelhar, L.W. 1990. Numerical Simulation of Solute 
Transport in Three-Dimensional, Randomly Heterogeneous Porous Media. Water 
Resources Research, 26, (10), 2541-2562. Washington, D.C.: American 
Geophysical Union. TIC: 224902. 
101490 
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. 
101060 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-16 November 2004 
USGS (U.S. Geological Survey) 2001. Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport Model. ANL-NBS-HS-000034 
REV 00 ICN 01. Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.20010405.0211. 
154625 
USGS 2001. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow 
and Transport Model. ANL-NBS-HS-000034 REV 01. Denver, Colorado: 
U.S. Geological Survey. ACC: MOL.20020209.0058. 
157611 
USGS 2004. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow 
and Transport Model. ANL-NBS-HS-000034 REV 01 Errata 002. Denver, 
Colorado: U.S. Geological Survey. ACC: MOL.20020209.0058; 
MOL.20020917.0136; DOC.20040303.0006. 
168473 
Vaniman, D.T.; Bish, D.L.; Chipera, S.J.; Carlos, B.A.; and Guthrie, G.D., Jr. 1996. 
Chemistry and Mineralogy of the Transport Environment at Yucca Mountain. 
Volume I of Summary and Synthesis Report on Mineralogy and Petrology Studies 
for the Yucca Mountain Site Characterization Project. Milestone 3665. 
Los Alamos, New Mexico: Los Alamos National Laboratory. 
ACC: MOL.19961230.0037. 
105946 
Vaniman, D.T.; Chipera, S.J.; Bish, D.L.; Carey, J.W.; and Levy, S.S. 2001. 
Quantification of Unsaturated-Zone Alteration and Cation Exchange in Zeolitized 
Tuffs at Yucca Mountain, Nevada, USA. Geochimica et Cosmochimica Acta, 65, 
(20), 3409-3433. New York, New York: Elsevier. TIC: 251574. 
157427 
Verma, S. and Aziz, K. 1997. A Control Volume Scheme for Flexible Grids in 
Reservoir Simulation. Proceedings, SPE Reservoir Simulation Symposium, 8-11, 
June 1997, Dallas, Texas. SPE 37999. Pages 215-227. Richardson, Texas: 
Society of Petroleum Engineers. TIC: 247097. 
143606 
Vesselinov, V.V.; Illman, W.A.; Hyun, Y.; Neuman, S.P.; Di Federico, V.; and 
Tartakovsky, D.M. 2001. Observation and Analysis of a Pronounced Permeability 
and Porosity Scale-Effect in Unsaturated Fractured Tuff. Fractured Rock 2001, 
An International Conference Addressing Groundwater Flow, Solute Transport, 
Multiphase Flow, and Remediation in Fractured Rock, March 26-28, 2001, 
Toronto, Ontario, Canada. Kueper, B.H.; Novakowski, K.S.; and Reynolds, D.A., 
eds. Smithville, Ontario, Canada: Smithville Phase IV. TIC: 249909. 
154706 
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. 
101062 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-17 November 2004 
Walker, G.E. and Eakin, T.E. 1963. Geology and Ground Water of Amargosa 
Desert, Nevada-California. Ground-Water Resources  Reconnaissance Series 
Report 14. Carson City, Nevada: State of Nevada, Department of Conservation 
and Natural Resources. TIC: 208665. 
103022 
Weeks, E.P. 1978. Field Determination of Vertical Permeability to Air in the 
Unsaturated Zone. Geological Survey Professional Paper 1051. Washington, 
D.C.: U.S. Government Printing Office. TIC: 218986. 
108841 
Wen, X-H. and Gomez-Hernandez, J.J. 1996. The Constant Displacement 
Scheme for Tracking Particles in Heterogeneous Aquifers. Ground Water, 34, (1), 
135-142. Worthington, Ohio: Water Well Journal Publishing. TIC: 246656. 
130510 
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. 
137305 
Whelan, J.F.; Moscati, R.J.; Roedder, E.; and Marshall, B.D. 1998. Secondary 
Mineral Evidence of Past Water Table Changes at Yucca Mountain, Nevada. 
High-Level Radioactive Waste Management, Proceedings of the Eighth 
International Conference, Las Vegas, Nevada, May 11-14, 1998. Pages 178-181. 
La Grange Park, Illinois: American Nuclear Society. TIC: 237082. 
108865 
White, A.F. 1979. Geochemistry of Ground Water Associated with Tuffaceous 
Rocks, Oasis Valley, Nevada. Professional Paper 712-E. Washington, D.C.: 
U.S. Geological Survey. TIC: 219633. 
101165 
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. 
108871 
White, A.F.; Claassen, H.C.; and Benson, L.V. 1980. The Effect of Dissolution of 
Volcanic Glass on the Water Chemistry in a Tuffaceous Aquifer, Rainier Mesa, 
Nevada. Geochemistry of Water. Geological Survey Water-Supply Paper 1535-Q. 
Washington, D.C.: U.S. Government Printing Office. TIC: 221391. 
101166 
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. 
108882 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-18 November 2004 
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. Geological Survey Professional Paper 712-C. 
Washington, D.C.: United States Government Printing Office. 
ACC: NNA.19870406.0201. 
101167 
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. 
100094 
Winterle, J.R. and La Femina, P.C. 1999. Review and Analysis of Hydraulic and 
Tracer Testing at the C-Holes Complex Near Yucca Mountain, Nevada. San 
Antonio, Texas: Center for Nuclear Waste Regulatory Analyses. TIC: 246623. 
129796 
Wollenberg, H.A.; Wang, J.S.Y.; and Korbin, G. 1983. An Appraisal of Nuclear 
Waste Isolation in the Vadose Zone in Arid and Semiarid Regions (with Emphasis 
on the Nevada Test Site). LBL-15010. Berkeley, California: University of 
California, Lawrence Berkeley Laboratory. TIC: 211058. 
163359 
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. 
149596 
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. 
100194 
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. 
101441 
Zyvoloski, G. 1983. Finite Element Methods for Geothermal Reservoir 
Simulation. International Journal for Numerical and Analytical Methods in 
Geomechanics, 7, (1), 75-86. New York, New York: John Wiley & Sons. 
TIC: 224068. 
101171 
Zyvoloski, G.; Kwicklis, E.; Eddebbarh, A.A.; Arnold, B.; Faunt, C.; and 
Robinson, B.A. 2003. The Site-Scale Saturated Zone Flow Model for Yucca 
Mountain: Calibration of Different Conceptual Models and their Impact on Flow 
Paths. Journal of Contaminant Hydrology, 62-63, 731-750. New York, 
New York: Elsevier. TIC: 254340. 
163341 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-19 November 2004 
Zyvoloski, G.A.; Robinson, B.A.; Dash, Z.V.; and Trease, L.L. 1997. Users 
Manual for the FEHM ApplicationA Finite-Element Heat- and Mass-Transfer 
Code. LA-13306-M. Los Alamos, New Mexico: Los Alamos National 
Laboratory. TIC: 235999. 
100615 
9.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
10 CFR 63. Energy: Disposal of High-Level Radioactive Wastes in a Geologic 
Repository at Yucca Mountain, Nevada. Readily available. 
156605 
AP-2.22Q, Rev. 1, ICN 1. Classification Analyses and Maintenance of the Q-List. 
Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: DOC.20040714.0002. 
AP-2.27Q, Rev. 1, ICN 5. Planning for Science Activities. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20041014.0001. 
AP-SI.1Q, Rev. 5, ICN 2. Software Management. Washington, D.C.: 
U.S. Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20030902.0003. 
AP-SIII.10Q, Rev. 2, ICN 7. Models. Washington, D.C.: U.S. Department of 
Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20040920.0002. 
LP-SI.11Q-BSC, Rev. 0, ICN 1. Software Management. Washington, D.C.: U.S. 
Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20041005.0008. 
9.3 SOURCE DATA, LISTED BY DATA TRACKING NUMBER 
GS000308312322.003. Preliminary Release of Field, Chemical, and Isotopic Data 
from the Nye County Early Warning Drilling Program (EWDP) Wells in Amargosa 
Valley, Nevada Collected Between 12/11/98 and 11/15/99. Submittal 
date: 03/16/2000. 
149155 
GS000508312332.001. Water-Level Data Analysis for the Saturated Zone Site-Scale 
Flow and Transport Model. Submittal date: 06/01/2000. 
149947 
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. 
150842 
GS010208312322.001. Uranium Concentrations and 234U/238U Activity Ratios 
Analyzed Between August, 1998 and April, 2000 for Saturated-Zone Well Water, 
Springs, and Runoff Collected between April, 1998 and November 1999. Submittal 
date: 03/30/2001. 
162908 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-20 November 2004 
GS010308312322.002. Chemical and Isotopic Data from Wells in Yucca Mountain 
Area, Nye County, Nevada, Collected between 12/11/98 and 11/15/99. Submittal 
date: 03/29/2001. 
162910 
GS010308312322.003. Field, Chemical and Isotopic Data from Wells in Yucca 
Mountain Area, Nye County, Nevada, Collected Between 12/11/98 and 11/15/99. 
Submittal date: 03/29/2000. 
154734 
GS010608312332.001. Potentiometric-Surface Map, Assuming Perched Conditions 
North of Yucca Mountain, in the Saturated Site-Scale Model. Submittal 
date: 06/19/2001. 
155307 
GS010608315215.002. Uranium and Thorium Isotope Data for Waters Analyzed 
Between January 18, 1994 and September 14, 1996. Submittal date: 06/26/2001. 
156187 
GS010808312322.004. Uranium and Uranium Isotopic Data for Water Samples from 
Wells and Springs in the Yucca Mountain Vicinity Collected Between December 1996 
and December 1997. Submittal date: 08/29/2001. 
156007 
GS010908312332.002. Borehole Data from Water-Level Data Analysis for the 
Saturated Zone Site-Scale Flow and Transport Model. Submittal date: 10/02/2001. 
163555 
GS010908314221.001. Geologic Map of the Yucca Mountain Region, Nye County, 
Nevada. Submittal date: 01/23/2002. 
162874 
GS011108312322.006. Field and Chemical Data Collected between 1/20/00 and 
4/24/01 and Isotopic Data Collected between 12/11/98 and 11/6/00 from Wells in the 
Yucca Mountain Area, Nye County, Nevada. Submittal date: 11/20/2001. 
162911 
GS021008312322.002. Stable Isotopic Data for Water Samples Collected between 
02/20/98 and 08/20/98 in the Yucca Mountain Area, Nye County, Nevada. Submittal 
date: 11/12/2002. 
162913 
GS021008312332.002. Hydrogeologic Framework Model for the Saturated-Zone 
Site-Scale Flow and Transport Model, Version YMP_9_02. Submittal 
date 12/09/2002. 
164363 
GS030208312332.001. HFM Final Output - Hydrogeologic Framework Model for the 
Saturated-Zone Site-Scale Flow and Transport Model. Submittal date: 02/10/2003. 
163087 
GS031108312322.003. Uranium Concentrations and 234U/238U Ratios for 
Ground-Water Samples from Boreholes ER-EC-7, ER-18-2, and UE-18R Collected 
between December 1999 and June 2000. Submittal date: 11/25/2003. 
166467 
GS040208312322.003. 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 01/15/98 and 08/15/98. Submittal date: 04/01/2004. 
172396 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-21 November 2004 
GS920408312321.003. Chemical Composition of Groundwater in the Yucca 
Mountain Area, Nevada 1971 - 1984. Submittal date: 04/24/1987. 
105937 
GS930108315213.002. Water Chemistry and Sample Documentation for Two 
Samples from Lathrop Wells Cone and USW VH-2. Submittal date: 01/15/1993. 
148109 
GS930108315213.004. Uranium Isotopic Analyses of Groundwaters from SW 
Nevada  SE California. Submittal date: 01/21/1993. 
145525 
GS930208318523.001. Temperature and Thermal Conductivity in Wells Near Yucca 
Mountain. Submittal date: 02/16/1993. 
145763 
GS930308312323.001. Chemical Composition of Groundwater and the Locations of 
Permeable Zones in the Yucca Mountain Area. Submittal date: 03/05/1993. 
145530 
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. 
145404 
GS931100121347.007. Selected Ground-Water Data for Yucca Mountain Region, 
Southern Nevada and Eastern California, Through December 1992. Submittal 
date: 11/30/1993. 
149611 
GS940908315213.005. U Concentrations and 234U/238U Ratios for Waters in Yucca 
Mountain Region. Submittal date: 09/22/1994. 
164673 
GS950208312232.003. Data, Including Water Potential, Pressure and Temperature, 
Collected from Boreholes USW NRG-6 and USW NRG-7A from Instrumentation 
through March 31, 1995. Submittal date: 02/13/1995. 
105572 
GS950408318523.001. Temperature, Thermal Conductivity, and Heat Flow Near 
Yucca Mountain, Nevada. Submittal date: 04/21/1995. 
107244 
GS950708315131.003. Woodrat Midden Age Data in Radiocarbon Years Before 
Present. Submittal date: 07/21/1995. 
106516 
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. 
148114 
GS951208312272.002. Tritium Analyses of Porewater from USW UZ-14, USW 
NRG-6, USW NRG-7A and UE-25 UZ#16 and of Perched Water from USW SD-7, 
USW SD-9, USW UZ-14 and USW NRG-7A from 12/09/92 to 5/15/95. Submittal 
date: 12/15/1995. 
151649 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-22 November 2004 
GS960308315131.001. Woodrat Midden Radiocarbon (C14). Submittal 
date: 03/07/1996. 
106517 
GS960408312323.002. Chemical and Isotopic Data Describing Water Samples 
Collected from 11 Springs and One Stream Within Death Valley National Park in 
1993, 1994, and 1995. Submittal date: 04/02/1996. 
162915 
GS960808312144.003. Hydrogeologic Evaluation and Numerical Simulation of the 
Death Valley Regional Ground-Water Flow System, Nevada and California, Using 
Geoscientific Information Systems. Submittal date: 08/29/1996. 
105121 
GS960908312232.012. Comparison of Air-Injection Permeability Values to 
Laboratory Permeability Values. Submittal date: 09/26/1996. 
114124 
GS960908312323.005. Hydrochemical Data Obtained from Water Samples Collected 
at Water Well ER-30-1 on 1/31/95 and 2/1/95. Submittal date: 09/10/1996. 
162916 
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. 
145405 
GS970708315215.008. Strontium Isotope Ratios and Isotope Dilution Data for 
Strontium for Two Samples Collected at UE-25 C#3, 12/4/96 and 2/19/97. Submittal 
date: 07/29/1997. 
164674 
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. 
145921 
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. 
149617 
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. 
146065 
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. 
145412 
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. 
118977 
GS990308312272.002. Isotopic Composition of Pore Water from Boreholes USW 
UZ-14 and USW NRG-6. Submittal date: 03/02/1999. 
145692 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-23 November 2004 
GS990808312322.001. Field and Isotopic Data From Ground Water Samples From 
Wells in the Amargosa Valley and NTS. Submittal date: 08/23/1999. 
149393 
GS990808312322.002. Chemical and Isotopic Data from Ground Water Samples 
Collected from Wells in the Amargosa. Submittal date: 08/23/1999. 
162917 
GS991208314221.001. Geologic Map of the Yucca Mountain Region. Submittal 
date: 12/01/1999. 
145263 
LA0002JF831222.001. 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. Submittal date: 02/25/2000. 
147077 
LA0002JF831222.002. 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 the Chloride Mass Balance Method. 
Submittal date: 02/25/2000. 
147079 
LA0202EK831231.002. Calculation of Corrected and Uncorrected Groundwater 
Carbon-14 Ages. Submittal date: 02/25/2002. 
165507 
LA0303PR831231.002. Estimation of Groundwater Drift Velocity from Tracer 
Responses in Single-Well Tracer Tests at Alluvium Testing Complex. Submittal 
date: 03/18/2003. 
163561 
LA0304TM831231.002. SZ Site-Scale Flow Model, FEHM Files for Base Case. 
Submittal date: 04/14/2003. 
163788 
LA0308RR831233.001. Regional Groundwater Flow Pathways in the Yucca 
Mountain Area Inferred from Hydrochemical and Isotopic Data. Submittal 
date: 08/25/2003. 
171890 
LA0309EK831223.001. UTM Coordinates for Selected Amargosa Desert Wells. 
Submittal date: 09/05/2003. 
165471 
LA0309EK831231.001. SZ Flow and Transport Model, FEHM Files for Tracer 
Transport. Submittal date: 09/02/2003. 
171887 
LA0309RR831233.001. Regional Groundwater Hydrochemical Data in the Yucca 
Mountain Area Used as Direct Inputs for ANL-NBS-HS-000021, REV 01. Submittal 
date: 09/05/2003. 
166546 
LA0309RR831233.002. Regional Groundwater Hydrochemical Data in the Yucca 
Mountain Area Used as Corroborative Data for ANL-NBS-HS-000021, REV 01. 
Submittal date: 09/05/2003. 
166548 
LA0310EK831231.001. SZ Geochemical Calculations, Groundwater Travel Times 171889 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-24 November 2004 
for Selected Wells. Submittal date: 10/16/2003. 
LA0310EK831232.001. SZ Geochemical Models, PHREEQC Files for Selected 
Groundwater Parameters. Submittal date: 10/02/2003. 
165995 
LA0311EK831223.001. Well Completion Summary Information for the Nye County 
EWDP, Phases I and II. Submittal date: 11/04/2003. 
165985 
LA0311EK831232.001. Hydrochemical Data Obtained from GEOCHEM.02 
Database. Submittal date: 11/06/2003. 
166068 
LA0311EK831232.002. Groundwater Hydrochemical Data from Nye County Early 
Warning Drilling Project Boreholes as Reported by Nye County. Submittal 
date: 11/04/2003. 
166069 
LA9909JF831222.010. Chloride, Bromide, Sulfate, and Chlorine-36 Analyses of ESF 
Porewaters. Submittal date: 09/29/1999. 
122733 
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. 
122736 
LAJF831222AQ97.002. Chlorine-36 Analyses of Packrat Urine. Submittal 
date: 09/26/1997. 
145401 
LAJF831222AQ98.011. Chloride, Bromide, Sulfate and Chlorine-36 Analyses of 
Springs, Groundwater, Porewater, Perched Water and Surface Runoff. Submittal 
date: 09/10/1998. 
145402 
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. 
151492 
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. 
151493 
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. 
151494 
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 
151495 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-25 November 2004 
Mountain, Nevada. Submittal date: 07/28/2000. 
MO0007GNDWTRIS.006. Isotopic Content of Groundwater from Selected Yucca 
Mountain Project WT 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. 
151496 
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. 
151497 
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. 
151508 
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. 
151509 
MO0007GNDWTRIS.010. 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. 
151500 
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. 
151501 
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. 
151504 
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. 
151507 
MO0007MAJIONPH.003. Major Ion 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. 
151513 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-26 November 2004 
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. 
151516 
MO0007MAJIONPH.005. Major Ion Content of Groundwater from 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. 
151517 
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. 
151518 
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. 
151519 
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. 
151521 
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. 
151522 
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. 
151523 
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. 
151524 
MO0007MAJIONPH.012. 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. 
151529 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-27 November 2004 
MO0007MAJIONPH.013. 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. 
151530 
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. 
151531 
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. 
151532 
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. 
151533 
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 Groundwater Flow 
Directions, Mixing and Recharge at Yucca Mountain, Nevada. Submittal 
date: 08/02/2000. 
151534 
MO0008NYE02997.033. EWDP Phase 1 Water and Elevation Data from Westbay 
Instrumented Wells, 05/06/99 - 10/18/99. Submittal date: 08/10/2000. 
155290 
MO0012URANISOT.000. Water - Selected Uranium Abundance and Isotope Ratios. 
Submittal date: 12/06/2000. 
153384 
MO0102DQRBTEMP.001. Temperature Data Collected from Boreholes Near Yucca 
Mountain in Early 1980s. Submittal date: 02/21/2001. 
154733 
MO0309THDPHRQC.000. Input Data File (PHREEQC.DAT) for Thermodynamic 
Data Software Code PHREEQC, Version 2.3. Submittal date: 09/22/2003. 
165529 
MO0405NYE05819.215. Manual Water Level Data for EWDP Phase I Wells from 
05/02 - 08/03, Phase II Wells from 05/02 - 08/03, Phase III Wells from 11/02 - 8/03 
and Phase IV Wells from 01/03 - 08/03. Submittal date: 05/20/2004. 
170539 
MO0407SEPFEPLA.000. LA FEP List. Submittal date: 07/20/2004. 170760 
MO9909NYEEWDP0.000. Phase I-Fiscal Year 1999 Nye County Early Warning 
Drilling Program Data Package. Submittal date: 09/16/1999. 
119613 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-28 November 2004 
SN0407T0504404.002. Distributed Recharge and Lateral Boundary Conditions for 
the Saturated Zone (SZ) Site-Scale Flow and Transport Model. Submittal 
date: 07/15/2004. 
170929 
SN9908T0581999.001. Recharge and Lateral Groundwater Flow Boundary 
Conditions for the Saturated Zone (SZ) Site-Scale Flow and Transport Model. 
Submittal date: 08/19/1999. 
132867 
SNT05082597001.003. TSPA-VA (Total System Performance Assessment-Viability 
Assessment) Saturated Zone (SZ) Base Case Modeling Analysis Results. Submittal 
date: 02/03/1998. 
129714 
9.4 OUTPUT DATA, LISTED BY DATA TRACKING NUMBER 
LA0304TM831231.001. SZ Flow and Transport Model, Hydrogeologic Surface Files. 
Submittal date: 04/7/2003. 
LA0304TM831231.002. SZ Site-Scale Flow Model, FEHM Files for Base Case. 
Submittal date: 04/14/2003. 
LA0409GZ831231.001. SZ Site-Scale Flow Model, FEHM Files for Alternate Model 
AM0. Submittal date: 09/09/2004. 
LA0409GZ831231.002. SZ Site-Scale Flow Model, FEHM Files for Alternate Model 
AM1. Submittal date: 09/13/2004. 
LA0409GZ831231.003. SZ Site-Scale Flow Model, FEHM Files for Alternate Model 
AM2. Submittal date: 09/14/2004. 
LA0409GZ831231.004. SZ Site-Scale Flow Model, FEHM Files for Alternate Model 
AM3. Submittal date: 09/14/2004. 
LA0409GZ831231.005. SZ Site-Scale Flow Model, FEHM Files for Alternate Model 
AM4. Submittal date: 09/14/2004. 
9.5 SOFTWARE CODES 
BSC (Bechtel SAIC Company) 2001. Software Code: PHREEQC. V2.3. PC, 
LINUX, Windows 95/98/NT, Redhat 6.2. 10068-2.3-00. 
155323 
BSC 2002. Software Code: PHREEQC. V2.3. PC. 10068-2.3-01. 157837 
Landmark Graphics. 1998. Software Code: STRATAMODEL. V4.1.1. SGI. 
10121-4.1.1-00. 
153238 
LANL (Los Alamos National Laboratory) 2000. Software Routine: 
READPATHS. V1.0. MDL-NBS-HS-000011. 
150459 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-29 November 2004 
LANL 2001. Software Code: LaGriT. V1.0. 10212-1.0-00. 149148 
LANL 2001. Software Code: NETPATH. V2.13. Platform: PC, OS: 
WINDOWS NT, DOS Emulation. 10303-2.13-00. 
149910 
LANL 2003. Software Code: FEHM. V2.20. SUN, PC. 10086-2.20-00. 161725 
LANL 2003. Software Code: fehm2tec. V 1.0. Sun, Solaris 2.7 and 2.8. 
11092-1.0-00. 
164654 
LANL 2003. Software Code: maketrac. V 1.1. Sun, SunOS 5.7 and 5.8. 
11078-1.1-00. 
164653 
LANL 2003. Software Code: prepare_features_for_surfer. V1.0. SUN OS 5.7, 
5.8. 11091-1.0-00. 
171911 
LANL 2003. Software Code: reformat_sz. V 1.0. Sun, Solaris 2.7 and 2.8. 
11079-1.0-00. 
164652 
LANL 2003. Software Code: STRAT2AVS. V 1.0. SGI with Irix64 operating 
system. 11028-1.0-00. 
163069 
LANL 2003. Sofware Code: write_temps. V1.0. SUN O.S. 5.7, SUN O.S. 5.8. 
11090-1.0-00. 
171891 
SNL (Sandia National Laboratories) 2002. Software Code: EXT_RECH. V 1.0. 
Sun - SunOS 5.7. 10958-1.0-00. 
163072 
SNL 2002. Software Code: Extract. V 1.0. Sun UltraSPARC - SunOS 5.7. 
10955-1.0-00. 
163070 
SNL 2002. Software Code: Extract. V 1.1. Sun UltraSPARC - SunOS 5.7. 
10955-1.1-00. 
163071 
SNL 2002. Software Code: Mult_Rech. V 1.0. Sun UltraSPARC - SunOS 5.7. 
10959-1.0-00. 
163073 
SNL 2002. Software Code: WTCONVYD. V 1.00. SUN,Solaris 8; PC, 
Windows 98. 10815-1.0-00. 
163835 
SNL 2002. Software Code: Xread_Distr_Rech. V 1.0. Sun 
UltraSPARC - SunOS 5.7. 10960-1.0-00. 
163074 
SNL 2002. Software Code: Xread_Distr_Rech_-UZ. V 1.0. Sun 
UltraSPARC - SunOS 5.7. 10961-1.0-00. 
163075 
SNL 2002. Software Code: Xread_Reaches. V 1.0. Sun UltraSPARC - SunOS 
5.7. 10962-1.0-00. 
163076 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 9-30 November 2004 
SNL 2002. Software Code: Xwrite_Flow_New. V 1.0-125. Sun 
UltraSPARC - SunOS 5.7. 10963-1.0-125-00. 
163077 
SNL 2002. Software Code: Zone. V 1.0. Sun UltraSPARC - SunOS 5.7. 
10957-1.0-00. 
163078 
Watermark Computing. 2002. Software Code: PEST. V5.5. SUN, PC, Linux. 
10289-5.5-00. 
161564 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 November 2004 
APPENDIX A 
GEOCHEMICAL AND ISOTOPIC CONSTRAINTS ON GROUNDWATER FLOW 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 November 2004 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-1 November 2004 
A1. PURPOSE 
The purpose of the work described in this appendix 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 evaluations that are based purely on hydraulic 
arguments. In this way, this appendix is intended as an independent corroboration of the 
saturated zone flow model presented in the main text of this report. 
This appendix is a revision of the Geochemical and Isotopic Constraints on Groundwater Flow 
Directions, Mixing, and Recharge at Yucca Mountain (BSC 2001 [DIRS 158606]). The 
revisions include the following: 
1. Analyze new data to determine chemical reactions in the groundwater system, the 
evolution of groundwater as it moves from upgradient source areas to downgradient 
areas of potential groundwater withdrawal, groundwater mixing relationships, and 
chemical and isotopic distributions of strontium and uranium. 
2. Correct groundwater 14C ages for water/rock interactions. 
3. Provide an analysis of groundwater recharge rates, flow directions and velocities, and 
mixing proportions of water from different source areas. 
4. Compare patterns of groundwater movement produced by the SZ flow model with 
flow patterns inferred from hydrochemical and isotopic data. 
Information supporting the resolution of several technical issues related to the saturated zone was 
also developed in this appendix: 
1. Groundwater residence times based on 14C 
2. Flow path lengths in alluvium and tuff. 
Addressing these and related issues will help in determining the performance of the saturated 
zone as a natural barrier to radionuclide migration. 
The physical and hydrochemical parameters summarized in this appendix are important controls 
on the transport of dissolved and colloidal species in the saturated zone. This information can be 
used in the SZ site-scale flow and SZ transport models to simulate the transport of radionuclides 
as breakthrough curves. These breakthrough curves are then used as input in the TSPA-LA 
calculations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-2 November 2004 
A2. NOT USED 
A3. SOFTWARE CODES 
The computer code, PHREEQC V2.3, 6.2.10068-2.3-00 (BSC 2001 [DIRS 155323]), used 
directly in this appendix, is public-domain geochemical software whose description is 
summarized in Table A3-1. The software was obtained from Software Configuration 
Management (SCM) and is appropriate for the license application. The code was used only 
within its range of validation as required by LP-SI.11Q-BSC, Software Management. Input files 
for this appendix are identified in Section A4; the outputs are listed in Section A7.2. 
Table A3-1. Software Used in Support of this Scientific Analysis 
Software 
Name and 
Version (V) 
Software 
Tracking 
Number (STN) 
Description/ 
Section Where Used 
Computer and 
Platform 
Identification Reference 
Date 
Baselined 
PHREEQC, 
V2.3 
10068-2.3-00 Used to speciate elements in 
groundwater, calculate mineral 
saturation indices, and calculate 
mixing fractions and chemical 
reactions required to produce 
observed groundwater 
compositions. PHREEQC is a 
C-language program developed 
by the U.S. Geological Survey 
(USGS). Used in Sections 
6.7.6.6.2 and 6.7.8. 
Windows 
95/98/NT; 
Compaq 
professional 
workstation 
AP400 
BSC (2001 
[DIRS 155323]) 
03/29/01 
FEHM 
V2.20 
10086-2.20-00 Flow modeling/flow and transport 
modeling used to illustrate 
groundwater flow paths. Used in 
Section 6.7.10. 
Sun workstation 
SunOS v. 5.7-5.8 
LANL (2003 
[DIRS 161725]) 
01/28/03 
reformat_sz 
V1.0 
11079-1.0-00 Used to reformat hydrochemical 
and isotopic data originally in a 
text format for input into 
PHREEQC. Written in Fortran 
77. Used in Sections 6.7.5, 
6.7.6.6.2, and 6.7.8. 
Solaris 2.7, 2.8 LANL (2003 
[DIRS 164652]) 
05/21/03 
maketrac 
V1.1 
11078-1.1-00 Used to create trac macro for 
FEHM. Used in Section 6.7.10. 
Sun workstation 
SunOS v. 5.7-5.8 
LANL (2003 
[DIRS 164653]) 
07/02/03 
fehm2tec 
V1.0 
11092-1.0-00 Used to reformat FEHM output 
for plotting with TECPLOT, V 8.0. 
Used in Section 6.7.10. 
Sun workstation 
Solaris 2.7, 2.8 
LANL (2003 
[DIRS 164654]) 
06/26/03 
The range of hydrochemical and isotopic data used in PHREEQC V2.3, STN: 10068-2.3-00 
(BSC 2001 [DIRS 155323]) is indicated by Tables A6-1 and A6-2. The results of all 
calculations using PHREEQC were checked with order-of-magnitude estimations. FEHM 
V2.20, STN: 10086-2.20-00 (LANL 2003 [DIRS 161725]) was used to illustrate groundwater 
flow paths predicted by the SZ (Table 6-17). The reformat_sz was used to reformat 
hydrochemical and isotopic data for input into PHREEQC; output from reformat_sz V1.0 
STN: 11079-1.0-00 (LANL 2003 [DIRS 164652]) was verified by visual inspection. Maketrac 
V1.1 STN: 11078-1.1-00 (LANL 2003 [DIRS 164654]) was used to help create the trac macro 
for FEHM, and fehm2tec V1.0 STN: 11092-1.0-00 (LANL 2003 [DIRS 164654]) was used to 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-3 November 2004 
reformat FEHM output for plotting with TECPLOT. The output from the maketrac and 
fehm2tec codes was verified by visual inspection of the FEHM results. 
A4. INPUTS 
Input data used in this appendix come from several sources, as summarized in Table A4-1 and 
Table A4-2. Table A4-3 lists the types of chemical and isotopic groundwater data presented by 
the sources in Table A4-1 and A4-2, including local data for the Yucca Mountain area and 
regional data for the Death Valley flow system and Nevada Test Site (NTS). The input data 
referenced in Tables A4-1, A4-2 and Table A4-3 represents geochemical and isotopic 
characteristics of perched water and groundwater near Yucca Mountain and hence is appropriate 
for the intended use. Data from the Death Valley flow system immediately surrounding Yucca 
Mountain are also presented to provide evidence for potential sources of groundwater found near 
Yucca Mountain and place the Yucca Mountain groundwater system within a regional 
perspective. The data presented for the area around Yucca Mountain within the SZ site-scale 
flow model domain (Figure A6-1) include representative historical data sets collected in the 
1960s through the 1990s, as well as more recent data from newly drilled wells. In the immediate 
Yucca Mountain area, nearly all data collected since Yucca Mountain came under consideration 
as a repository were evaluated. Data from the outlying areas were selected to provide more 
complete geographic coverage but are not nearly as comprehensive as the data sets in the Yucca 
Mountain area. When both new data (1990s and later) and historical data sets were available in 
an area, emphasis was generally given to the newer data sets because they were typically more 
comprehensive in terms of the suite of chemicals and isotopes that were analyzed. This 
emphasis was especially true for the areas north of Yucca Mountain in the Timber Mountain, 
Beatty Wash, Fortymile Canyon and Oasis Valley areas. In the west-central Amargosa Desert, 
the data represent a blend of historic and recently collected data because of uncertainty in the 
effects of recent groundwater development on groundwater compositions. Elsewhere (for 
example, in Amargosa Flats), historical data sets were used where they provided the only 
representative hydrochemical data for an area. 
Data contained in the DTNs and other sources listed in Tables A4-1, A4-2 and A4-3 are 
summarized for each sample/well location in Section A6.3 (Tables A6-1 and A6-2) where areal 
distributions and scatterplots of the hydrochemical and isotopic data are discussed and portrayed 
on figures. Where multiple sets of data were available for a location/sample, these data were 
averaged to derive the values shown in those tables, and it is these compiled values that are 
plotted in the figures of Section A6.3. Groundwater samples taken from different depth intervals 
in the same well were evaluated to examine the trends of groundwater composition with depth in 
the well (see Section A6.3.3). Groundwater sample depths and information on the geologic units 
present in the sampled interval are given in Table A4-3 to aid in understanding the causes of 
similarities or differences in groundwater compositions from particular geographic areas. 
Tables A4-1 to A4-3 provide the DTN links back to the original data used to generate the 
compiled and plotted values listed and shown in Section A6. 

MDL-NBS-HS-000011 REV 02 A-4 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-1. Sources of Data 
DTN Description DTN Tables Used1 
MO0007GNDWTRIS.004 [DIRS 151494] S00368_001 Chemical and isotopic data from borehole TW-5 
MO0007MAJIONPH.002 [DIRS 151507] S00352_001 
Chemical data from the Nye County EWDP Wells in Amargosa Valley, 
Nevada, collected between 12/11/98 and 11/15/99. 
MO0007MAJIONPH.015 [DIRS 151532] S00365_001 
Chemical data from borehole NDOT collected 5/17/95 MO0007MAJIONPH.009 [DIRS 151522] S00359_001 
MO0007GNDWTRIS.006 [DIRS 151496] S00370_001 Chemical and isotopic data from boreholes WT-7, WT-10, WT#12, WT#14, 
and WT#15 MO0008MAJIONPH.017 [DIRS 151534] S00383_001 
Stable isotope ratios and radiocarbon data for WT#12, WT#14, and WT#15 MO0007GNDWTRIS.007 [DIRS 151497] S00371_001 
MO0007GNDWTRIS.008 [DIRS 151508] S00372_001 Chemical and isotopic data from test well UE-25 p#1, Yucca Mountain area, 
Nye County, Nevada MO0007MAJIONPH.010 [DIRS 151523] S00360_001 
MO0007GNDWTRIS.009 [DIRS 151509] S00373_001 
MO0007MAJIONPH.011 [DIRS 151524] S00361_001 
Chemical and isotopic data for groundwater in the Yucca Mountain area, 
Nevada 1971 to 1984 
MO0007GNDWTRIS.010 [DIRS 151500] S00374_001 
Chemical composition of groundwater from ONC#1 MO0007MAJIONPH.004 [DIRS 151516] S00354_001 
MO0007MAJIONPH.016 [DIRS 151533] S00378_001 Chemical and isotopic data from perched groundwater at selected YMP 
boreholes MO0007GNDWTRIS.013 [DIRS 151504] S00377_001 
Chemical analyses of water from selected wells and springs in the Yucca 
Mountain area, Nevada, and southeastern California 
MO0007MAJIONPH.012 [DIRS 151529] S00362_001 
Chemical composition of groundwater in the Yucca Mountain area MO0007MAJIONPH.013 [DIRS 151530] S00363_001 
MO0007GNDWTRIS.011 [DIRS 151501] S00375_001 Chemical and isotopic data for groundwater in the west-central Amargosa 
Desert, Nevada MO0007MAJIONPH.014 [DIRS 151531] S00364_001 
MO0007GNDWTRIS.005 [DIRS 151495] S00369_001 Selected groundwater data for Yucca Mountain region, southern Nevada, 
through December 1992 MO0007MAJIONPH.008 [DIRS 151521] S00358_001 
Hydrochemical database for the Death Valley Region MO0007MAJIONPH.006 [DIRS 151518] S00356_001 
MO0007GNDWTRIS.003 [DIRS 151493] S00367_001 Chemical and isotopic data for groundwater samples collected at boreholes 
USW UZ-14, UE-25 WT#3, and USW WT-17 MO0007MAJIONPH.005 [DIRS 151517] S00355_001 
Chemical composition of groundwater from UZ#16 MO0007MAJIONPH.007 [DIRS 151519] S00357_001 
MO0007GNDWTRIS.002 [DIRS 151492] S00366_001 Chemical and isotopic data for borehole USW G-2 
MO0007MAJIONPH.003 [DIRS 151513] S00353_001 
Chemical and isotopic data from the CIND-R-LITE well samples collected on 
5/17/95 and 9/6/95 
GS000700012847.001 [DIRS 150842] S00446_001 
MDL-NBS-HS-000011 REV 02 A-5 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-1. Sources of Data (Continued) 
DTN Description DTN Tables Used1 
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 [DIRS 148114] S96068_001 to S96068_003, 
S96068_010, 
S96068_011, 
S96068_015 to S96068_018, 
S96068_032, 
S96068_036 to S96068_040, 
S96068_042, 
S96068_043 
d18O and dD stable isotope analyses of borehole waters from GEXA Well 4 
and VH-2 
GS970708312323.001 [DIRS 145405] S97550_001 
S97550_002 
Uranium concentrations and 234U/238U ratios from spring, well, runoff, and 
rainwater collected from the NTS and Death Valley vicinities and analyzed 
between 01/15/98 and 08/15/98 
GS980908312322.009 [DIRS 118977] S99222_001 
Water chemistry and sample documentation for two samples from Amargosa 
Valley (formerly Lathrop Wells) cone and USW VH-2 
GS930108315213.002 [DIRS 148109] S98045_002 to S98045_010, 
S98045_023, S98045_029 
Uranium isotopic analyses of groundwater from SW NevadaSE California GS930108315213.004 [DIRS 145525] S96290_001 
S96290_002 
Stable isotopic data for water samples collected between 02/20/98 and 
08/20/98 in the Yucca Mountain area, Nye County, Nevada 
GS021008312322.002 [DIRS 162913] S02343_001 
S02343_002 
Field and isotopic data from groundwater samples from wells in the 
Amargosa Valley and NTS 
GS990808312322.001 [DIRS 149393] S99384_001 
S99384_002 
Chemical and isotopic data from groundwater samples collected from wells in 
the Amargosa 
GS990808312322.002 [DIRS 162917] S99385_001 
S99385_002 
Field, chemical, and isotopic data from wells in the Yucca Mountain area, Nye 
County, Nevada, collected between 12/11/98 and 11/15/99 
GS010308312322.003 [DIRS 154734] S01053_001 
S01053_002 
S01053_004 
Field and chemical data collected between 1/20/00 and 4/24/01 and isotopic 
data collected between 12/11/98 and 11/6/00 from wells in the Yucca 
Mountain area, Nye County Nevada 
GS011108312322.006 [DIRS 162911] S01174_001 
S01174_002 
Uranium and thorium isotope data for waters analyzed between January 18, 
1994, and September 14, 1996 
GS010608315215.002 [DIRS 156187] S01134_001 
Uranium and uranium isotope data for water samples from wells and springs 
in the Yucca Mountain vicinity collected between December 1996 and 
December 1997 
GS010808312322.004 [DIRS 156007] S01132_001 
Uranium concentrations and 234U/238U ratios for waters in Yucca Mountain 
region 
GS940908315213.005 [DIRS 164673] S96241_002 
S96241_003 
MDL-NBS-HS-000011 REV 02 A-6 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-1. Sources of Data (Continued) 
DTN Description DTN Tables Used1 
Hydrochemical data obtained from water samples collected at water well ER- 
30-1 on 1/31/95 and 2/1/95 
GS960908312323.005 [DIRS 162916] S97098_002 to S97098_005, 
S97098_013, 
S97098_017 to S97098_021, 
S97098_028 to S97098_031 
Strontium isotope ratios and isotope dilution data for strontium for two 
samples collected at UE-25 c#3, 12/4/96 and 2/19/97 
GS970708315215.008 [DIRS 164674] S97527_001 
S97527_002 
Tritium analyses of pore water from USW UZ-14, USW NRG-6, USW NRG- 
7A, and UE-25 UZ#16 and of perched water from USW SD-7, USW SD-9, 
USW UZ-14, and USW NRG-7A from 12/09/92 to 5/15/95 
GS951208312272.002 [DIRS 151649] S01175_002 
Chloride, bromide, sulfate and chlorine-36 analyses of springs, groundwater, 
pore water, perched water, and surface runoff 
LAJF831222AQ98.011 [DIRS 145402] S98328_001 
SZ site-scale flow model, FEHM files for SZ site-scale flow model LA0304TM831231.002 [DIRS 163788]  
Thermodynamic characteristics input file required to run PHREEQC MO0309THDPHRQC.000 [DIRS 165529] S03316_001 
Uranium activity ratios of pore waters from upper lithophysal unit of Topopah 
Spring tuff 
MO0012URANISOT.000 [DIRS 153384]  
Field, chemical, and isotopic data from a precipitation sample collected 
behind the service station in area 25 and groundwater samples collected at 
boreholes UE-25 c#2, UE-25 c#3, USW UZ-14, UE-25 WT#3, USW WT-17, 
and USW WT-24, between 10/06/97 and 07/01/98 (Only the data for WT-24 
were used as input from this DTN.) 
GS980908312322.008 [DIRS 145412] S98383_001, 003, 005 to 007, 009, 
014, 016, 018, 022, 024, 025, 028, 
031, 038, 041 to 044, 046 
1 Names of the tables within each DTN that were sources of data 

MDL-NBS-HS-000011 REV 02 A-7 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-2. Sources of Data and Other Information 
Information Used Reference (DTN) Source of Data Used 
Chloride, bromide, sulfate, and chlorine-36 analyses of ESF pore waters LA9909JF831222.010 [DIRS 122733] S99410_001 
Chloride, bromide, and sulfate analyses of pore water extracted from ESF Niche 3566 
(Niche #1) and ESF 3650 (Niche #2) drill core 
LA9909JF831222.012 [DIRS 122736] S99412_001 
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 [DIRS 147077] S00142_001 
Apparent infiltration rates in PTn units from USW UZ-7A, USA 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 the chloride mass-balance method 
LA0002JF831222.002 [DIRS 147079] S00143_001 
S00143_002 
S00143_003 
Uranium and thorium isotopic data from secondary minerals in the ESF collected 
between 02/15/97 and 09/15/97 
GS970808315215.012 [DIRS 145921] S97566_001 
S97566_003 
S97566_006 
Chemical and isotopic data from wells in Yucca Mountain area, Nye County, Nevada 
collected between 12/11/98 and 11/15/99 
GS010308312322.002 [DIRS 162910] S01052_001 
Uranium concentrations and 234U/238U activity ratios analyzed between August 1998 
and April 2000 for saturated-zone well water, springs, and runoff collected between 
April 1998 and November 1999 
GS010208312322.001 [DIRS 162908] S01051_001 
Chemical and isotopic data describing water samples collected from 11 springs and 
one stream within Death Valley National Park in 1993, 1994, and 1995 
GS960408312323.002 [DIRS 162915] S00176_001 
Field, chemical, and isotopic data from a precipitation sample collected behind the 
service station in area 25 and groundwater samples collected at boreholes UE-25 c#2, 
UE-25 c#3, USW UZ-14, UE-25 WT#3, USW WT-17, and USW WT-24, between 
10/06/97 and 07/01/98 
GS980908312322.008 [DIRS 145412] S98383_001, 
S98383_003, 
S98383_005, 
S98383_006, 
S98383_007, 
S98383_009, 
S98383_014, 
S98383_016, 
S98383_018, 
S98383_022, 
S98383_024, 
S98383_025, 
S98383_028, 
S98383_031, 
S98383_038, 
S98383_041 to 
S98383_044, 
S98383_046 
Selected groundwater data for Yucca Mountain region, southern Nevada, and eastern 
California, through December 1992 
GS931100121347.007 [DIRS 149611] S96375_006, 
S96375_007 
MDL-NBS-HS-000011 REV 02 A-8 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-2. Sources of Data and Other Information (Continued) 
Information Used Reference (DTN) Source of Data Used 
Water chemistry data from samples collected at borehole USW WT-24 between 
10/06/97 and 12/10/97 
GS980108312322.005 [DIRS 149617] S98308_001, 
S98308_006, 
S98308_007, 
S98308_009, 
S98308_010, 
S98308_015, 
S98308_019, 
S98308_026, 
S98308_027, 
S98308_029, 
S98308_031, 
S98308_033, 
S98308_036 
S98308_038 
Chemical composition of groundwater and the locations of permeable zones in the 
Yucca Mountain area 
GS930308312323.001 [DIRS 145530] S97314_008, 
S97314_017, 
S97314_018 
Chemical composition of groundwater in the Yucca Mountain area, Nevada, 1971 to 
1984 
GS920408312321.003 [DIRS 105937] S97126_009, 
S97126_018, 
S97126_019 
Selected groundwater hydrochemical and isotopic data from Geochem02.mdbthe 
Department of Energys comprehensive water quality database for groundwater in the 
vicinity of the Nevada Test Site (rev. 4) 
LA0311EK831232.001 [DIRS 166068]  
Hydrochemical data from field tests 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 
GS930908312323.003 [DIRS 145404] S96076_001 
Isotopic compositions of pore water from boreholes USW UZ-14 and USW NRG-6 GS990308312272.002 [DIRS 145692] S00254_001 
Groundwater strontium isotope data from selected Nye County Early Warning Drilling 
Program borehole 
LA0311EK831232.002 [DIRS 166069]  
Chemical composition of groundwater in the Yucca Mountain area, Nevada, 1971-1984 Benson and McKinley (1985 
[DIRS 101036]) 
Tables 1 and 5 
Hydrochemical database for the Yucca Mountain area, Nye County, Nevada Oliver and Root (1997 [DIRS 100069], 
attached file yucca.xls) 
Hydrochemical, isotope 
and summary worksheets 
234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of 
Yucca Mountain 
Paces et al. (2002 [DIRS 158817]) Table 1, Appendix A 
Sources and mechanisms of recharge for groundwater in the west-central Amargosa 
Desert, Nevadaa geochemical interpretation 
Claassen (1985 [DIRS 101125]) Table 1 
MDL-NBS-HS-000011 REV 02 A-9 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-2. Sources of Data and Other Information (Continued) 
Information Used Reference (DTN) Source of Data Used 
Chemical and isotopic data for groundwater in southern Nevada. Rose et al. (1997 [DIRS 144725]) Tables 2, 3, and 4 
Preliminary report on the isotope hydrology investigations at the Nevada Test Site: 
Hydrologic Resources Management Program, FY 19921993 
Davisson et al. (1994 [DIRS 162939]) Tables 1 and 2 
Groundwater chemistry at the Nevada Test Site: data and preliminary interpretations Chapman and Lyles (1993 
[DIRS 162940]) 
Appendix B, Figs. 10, 12, 
and 14 
Well completion summary information for the Nye County EWDP, Phases I and II LA0311EK831223.001 [DIRS 165985]  
Well completion data and spring discharge area lithologies for the PM-OV area Rose et al. (2002 [DIRS 162938]) Appendix A 
UTM coordinates for selected Amargosa Desert wells LA0309EK831223.001 [DIRS 165471] spreadsheet 
Claassen_coord.xls 
Borehole data from water-level analysis for the SZ site-scale flow and transport model GS010908312332.002 [DIRS 163555] S02298_001 
Uranium isotopic data for saturated- and unsaturated-zone waters collected by non- 
YMP personnel between May 1989 and August 1997 
GS980208312322.006 [DIRS 146065] S98201_001 
S98201_002 
Uranium concentrations and 234U/238U ratios for groundwater samples from boreholes 
ER-EC-7, ER-18-2, and UE-18r, collected between December 1999 and June 2000 
GS031108312322.003 [DIRS 166467]  

MDL-NBS-HS-000011 REV 02 A-10 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Oasis Valley/Northwest Amargosa 
ER-EC-08 ER-EC-08 1 532764 4106142 OV/NWA Oasis Valley/Northwest 
Amargosa 
(192.6320.0) 
(423.1474.9) 
(495.6606.6)4 
Tfb 
Tmaw 
Tmap4 
DTN: LA0311EK831232.001 
(DIRS 166068), 7/23/99, 6/28/00 
and 7/12/00 samples 
ER-OV-01 ER-OV-01 2 528417 4104084 OV/NWA Oasis Valley/Northwest 
Amargosa 
(45.751.8)8 Tuff8 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/8/97 sample; 
GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
ER-OV-06a ER-OV-06a 3 528417 4104084 OV/NWA Oasis Valley/Northwest 
Amargosa 
(154.2160.3)8 Tuff8 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/7/97 and 
11/8/97 samples; 
GS010808312322.004 
(DIRS 156007), U 
concentrations and isotopes 
ER-OV-05 ER-OV-05 4 520280 4099809 OV/NWA Oasis Valley/Northwest 
Amargosa 
(51.857.9)8 Alluvium8 DTN: LA0311EK831232.001 
(DIRS 166068), 11/7/97 sample 
ER-OV-02 ER-OV-02 5 526310 4098716 OV/NWA Oasis Valley/Northwest 
Amargosa 
(51.857.9)8 colluvial and 
alluvial 
gravel8 
DTNs: LA0311EK831232.001 
(DIRS 166068), 11/11/97 
sample); GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
Springdale 
Upper Well 
(10S/47E- 
32adc) 
Springdale 
Upper Well 
(10S/47E- 
32adc) 
6 523522 4097506 OV/NWA Oasis Valley/Northwest 
Amargosa 
open borehold 
(depth not 
reported) 
tuff breccia 
or alluvium4 
DTNs: LA0311EK831232.001 
(DIRS 166068), 11/12/97 
sample; GS010808312322.004 
(DIRS 156007), U 
concentrations and isotopes 
Goss Springs 
North 
(11S/47E- 
10bad) 
Goss Springs 
North 
(11S/47E- 
10bad) 
7 526100 4094647 OV/NWA Oasis Valley/Northwest 
Amargosa 
0.0 (spring) not reported DTNs: LA0311EK831232.001 
(DIRS 166068), 11/13/97 
sample; GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
MDL-NBS-HS-000011 REV 02 A-11 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Oasis Valley/Northwest Amargosa (Continued) 
ER-OV-03a ER-OV-03a 8 526299 4094587 OV/NWA Oasis Valley/Northwest 
Amargosa 
(67.173.2)8 tuff8 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/9/97 sample; 
GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
ER-OV-03a3 ER-OV-03a3 9 526299 4094587 OV/NWA Oasis Valley/Northwest 
Amargosa 
(34.440.5)8 Tma, tuff8 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/9/97 sample; 
GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
ER-OV-03a2 ER-OV-03a2 10 526299 4094587 OV/NWA Oasis Valley/Northwest 
Amargosa 
(183.5189.6)8 Not reported DTNs: LA0311EK831232.001 
(DIRS 166068), 11/9/97 sample; 
GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
Goss Spring 
(11S/47E- 
10bcc) 
Goss Spring 
(11S/47E- 
10bcc) 
11 526061 4093440 OV/NWA Oasis Valley/Northwest 
Amargosa 
0.0 (spring)2 Tv2 DTN: LA0311EK831232.001 
(DIRS 166068), 9/7/95 sample 
ER-OV-04a ER-OV-04a 12 525671 4089316 OV/NWA Oasis Valley/Northwest 
Amargosa 
(33.839.9)8 Alluvium8 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/7/97 
sample;GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
Beatty Well no. 
1 (Wat&Sanit 
Distr) 
Beatty Well 
no. 1 
(Wat&Sanit 
Distr) 
13 521378 4085329 OV/NWA Oasis Valley/Northwest 
Amargosa 
(30.0-48.8) Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 2/11/97 and 
4/28/97 samples 
MDL-NBS-HS-000011 REV 02 A-12 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Oasis Valley/Northwest Amargosa (Continued) 
Bond Gold 
Mining #1 
Bond Gold 
Mining #1 
14 516203 4074502 OV/NWA Oasis Valley/Northwest 
Amargosa 
Not reported Qal13 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, Alk, ions, 
d18O, dD, d13C); 
GS011108312322.006 (DIRS 
162911), 14C, d18O, dD, d13C, 
d34S; GS010208312322.001 
(DIRS 162908), 
U-concentrations and isotopes; 
GS010308312322.002 
(DIRS 162910),U concentrations 
US Ecology 
MW-313 
US Ecology 
MW-313 
15 527666 4069293 OV/NWA Oasis Valley/Northwest 
Amargosa 
open borehole 
(depth not 
reported) 
Qal13 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, Alk, ions, 
d18O, dD, d13C; 
GS011108312322.006 
(DIRS 162911), 14C, d18O, dD, 
d13C, d34S; 
GS010208312322.001 
(DIRS 162908), 
U-concentrations and isotopes; 
GS010308312322.002 (DIRS 
162910), U concentrations 
US Ecology 
MW-600 
US Ecology 
MW-600 
16 527666 4069293 OV/NWA Oasis Valley/Northwest 
Amargosa 
open borehole 
(depth not 
reported) 
Qal13 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, Alk, ions, 
d18O, dD, d13C; 
GS011108312322.006 
(DIRS 162911), 14C, d18O, dD, 
d13C, d34S; 
GS010208312322.001 
(DIRS 162908), Uconcentrations 
and isotopes; 
GS010308312322.002 (DIRS 
162910), U concentrations 
Nucl. Eng. Co. NEC Well 17 527519 4068738 OV/NWA Oasis Valley/Northwest 
Amargosa 
open borehole 
(86180)3 
QTal2 DTNs: MO0007GNDWTRIS.011 
(DIRS 151501). d13C, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C 
MDL-NBS-HS-000011 REV 02 A-13 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Oasis Valley/Northwest Amargosa (Continued) 
US Ecology 
MR-3 
US Ecology 
MR-3 
18 527395 4068707 OV/NWA Oasis Valley/Northwest 
Amargosa 
open borehole 
(depth not 
reported) 
Qal13 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, Alk, d18O, 
dD, d13C; GS011108312322.006 
(DIRS 162911), d18O, dD, d13C, 
d34S; GS010308312322.003 
(DIRS 154734), 14C; 
GS010208312322.001 
(DIRS 162908), 
U-concentrations and isotopes 
Timber Mountain 
UE-18r UE-18r 19 549322 4109762 TM Timber Mountain 5094,6 Tm, debris 
flow4 
DTNs: LA0311EK831232.001 
(DIRS 166068), 7/11/91,8/11/92 
and 12/9/99 samples; 
GS031108312322.003 
(DIRS 154734), U-isotopes 
ER-18-2 ER-18-2 20 555725 4106389 TM Timber Mountain (411.9758.0)4 Tmar4 DTNs: LA0311EK831232.001 
(DIRS 166068), 3/21/00 sample; 
GS031108312322.003 
(DIRS 154734), U-Isotopes 
ER-EC-05 ER-EC-05 21 538702 4106389 TM Timber Mountain (356.3439.8) 
(559.3654.1) 
(688.7755.9)4 
Ttc 
Tfbr,Tfbw 
Tmap4 
DTNs: LA0311EK831232.001 
(DIRS 166068), 7/8/99,5/4/00, 
and 5/25/00 samples; 
GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
Coffers Ranch 
Windmill Well 
Coffers 
Ranch 
Windmill Well 
22 539421 4095192 TM Timber Mountain (109.8146.3)4 Not reported DTNs: LA0311EK831232.001 
(DIRS 166068), samples from 
1994 through 1997; 
GS010808312322.004 
(DIRS 156007), U 
concentrations and isotopes 
MDL-NBS-HS-000011 REV 02 A-14 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Timber Mountain (Continued) 
ER-OV-03c ER-OV-03c 23 535494 4094374 TM Timber Mountain (156.1162.2)4,8 Tma4 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/10/97 
sample; GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
ER-EC-07 ER-EC-07 24 546484 40931217 TM Timber Mountain (272.8312.4) 
(351.4399.3)4 
Tfb,Tfl4 DTNs: LA0311EK831232.001 
(DIRS 166068), 8/7/99, 
4/28/2000 and 6/5/00 samples; 
GS031108312322.003 
(DIRS 166467), U-isotopes 
Fortymile Wash - North 
Water Well 8 Water Well 8 25 563113 4113275 FMW-N Fortymile Wash - North 3776 Tv2 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/4/97 sample; 
GS040208312322.003 
(DIRS 172396), 
U concentrations and isotopes 
Test Well 1 
(USGS HTH 
#1) 
Test Well 1 
(USGS HTH 
#1) 
26 569000 4112499 FMW-N Fortymile Wash - North 6246 Tv5 DTN: LA0311EK831232.001 
(DIRS 166068), 8/13/92 sample 
UE-18t UE-18t 27 559591 4109095 FMW-N Fortymile Wash - North (577.9792.5)4 Tm4 DTN: LA0311EK831232.001 
(DIRS 166068), 9/23/88 sample 
ER-30-1 
(upper) 
ER-30-1 
(upper) 
28 560805 4100463 FMW-N Fortymile Wash - North (179.1185.2)4 Basaltic 
lava4 
DTNs: GS960908312323.005 
(DIRS 162916 ), ions and most 
isotopes; GS950808312322.001 
(DIRS 148114), T, pH, Alkalinity, 
87Sr/86Sr 
ER-30-1 
(lower) 
ER-30-1 
(lower) 
29 560805 4100463 FMW-N Fortymile Wash - North (227.2233.3)4 Gravelly 
sand4 
DTNs: GS960908312323.005 
(DIRS 162916 ), ions and most 
isotopes; GS950808312322.001 
(DIRS 148114), T, pH, Alkalinity, 
87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-15 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  North (Continued) 
a#2(dp) 30 2473541 Th2 UE-29 a#2 
a#2(sh) 31 
555753 4088351 FMW-N Fortymile Wash - North 
872131 Th2 
DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS010808312322.004 
(DIRS 156007), U 
concentrations and isotopes; 
GS930308312323.001 
(DIRS 145530 ), T, F, Sr2+ 
UE-29a#1 
HTH 
UE-29a#1 
HTH 
32 555758 4088341 FMW-N Fortymile Wash - North (10.765.5)4 Rhyolite4 DTNs: LA0311EK831232.001 
(DIRS 166068), 11/6/97 sample; 
GS010808312322.004 
(DIRS 156007), 
U concentrations and isotopes 
UE-25 WT#15 WT#15 33 554034 4078702 FMW-N Fortymile Wash - North Open borehole 
(354415)9 
Tpt9 
UE-25 WT#14 WT#14 34 552630 4077330 FMW-N Fortymile Wash - North open borehole 
(346399)9 
Tpt,Tac9 
DTNs: MO0007GNDWTRIS.007 
(DIRS 151497), d18O, dD, d13C, 
14C; MO0007GNDWTRIS.006 
(DIRS 151496), d18O, dD, d13C, 
14C; MO0008MAJIONPH.017 
(DIRS 151534), C 
UE-25 J-13 J-13 35 554017 4073517 FMW-N Fortymile Wash - North (303-424) 
(820-1009)9 
Tpt 
Tct,Tlr9 
UE-25 J-12 J-12 36 554444 4068774 FMW-N Fortymile Wash - North open borehole 
(227271)9 
Tpt9 
DTNs: MO0007GNDWTRIS.010 
(DIRS 151500). d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930108315213.004 
(DIRS 145525), U 
concentrations and isotopes; 
GS930308312323.001 (DIRS 
145530), T, F, Sr2+; 
LA0311EK831232.001 (DIRS 
166068), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-16 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  North (Continued) 
UE-25 JF#3 JF#3 37 554498 4067974 FMW-N Fortymile Wash - North open borehole 
(216347)15 
Tv15 DTNs: MO0007GNDWTRIS.005 
(DIRS 151495), d18O, dD, d13C, 
14C; MO0007MAJIONPH.008 
(DIRS 151521), C; 
GS930908312323.003 
(DIRS 145404), F, Sr2+; 
GS930108315213.004 
(DIRS 145525), 
U concentrations and isotopes; 
LA0311EK831232.001 
(DIRS 166068), 87Sr/86Sr 
Solitario Canyon Wash 
H-6(bh) 38 open borehole 
(5261220)1 
Tcb/Tct2 DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930308312323.001 
(DIRS 145530), (T, F, Sr2+); 
H-6(Tct) 39 7538351 Tct2 
USW H-6 
H-6(Tcb) 40 
546188 4077816 SCW Solitario Canyon Wash 
6086461 Tcb2 
DTN: MO0007GNDWTRIS.010 
(DIRS 151500), (d18O, dD, d13C, 
14C); MO0007MAJIONPH.012 
(DIRS 151529), (C);Benson and 
McKinley 1985 (DIRS 101036), 
T, F, Sr2+ 
MDL-NBS-HS-000011 REV 02 A-17 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Solitario Canyon Wash (Continued) 
USW WT-7 WT-7 41 546151 4075474 SCW Solitario Canyon Wash open borehole 
(421491)9 
Tpt,Tcp9 DTNs: MO0007GNDWTRIS.006 
(DIRS 151496), d18O, d13C; 
MO0008MAJIONPH.017 
(DIRS 151534), C; 
LA0311EK831232.001 
(DIRS 166068), F, Sr2+, 
87Sr/86Sr; Paces et al. 2002 
(DIRS 158817), Table 1, 
U concentrations and isotopes 
USW WT-10 WT-10 42 545964 4073378 SCW Solitario Canyon Wash open borehole 
(347431)9 
Tpt9 DTNs: MO0007GNDWTRIS.006 
(DIRS 151496), d18O, dD, d13C, 
14C; MO0008MAJIONPH.017 
(DIRS 151534), C; 
DTN: LA0311EK831232.001 
(DIRS 166068), (F, Sr2+, 
87Sr/86Sr); ; Paces et al. 2002 
(DIRS 158817), Table 1, 
U concentrations and isotopes 
Yucca Mountain  Crest 
USW G-2 G-2 43 548143 4082542 YM-CR Yucca Mountain  Crest 533-79210 Tpt,Tac10 DTNs: MO0007GNDWTRIS.002 
(DIRS 151492), d18O, dD, d13C, 
14C; MO0007MAJIONPH.003 
(DIRS 151513), C; 
GS010608315215.002 
(DIRS 156187), U 
concentrations and isotopes; 
LA0311EK831232.001 
(DIRS 166068), F, Sr2+, 
87Sr/86Sr 
USW WT-24 USW WT-24 44 548691 4081898 YM-CR Yucca Mountain  Crest 68811 Not reported DTN: GS980908312322.008 
(DIRS 145412), 4/24/98 sample; 
Paces et al. 2002 
(DIRS 158817), Table 1 
MDL-NBS-HS-000011 REV 02 A-18 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  Crest (Continued) 
UZ-14 (sh) 45 bailed (579)11 Tcp USW UZ-14 
UZ-14 (dp) 46 
548032 4080260 YM-CR Yucca Mountain  Crest 
bailed (655)11 Tcb 
DTNs: MO0007GNDWTRIS.003 
(DIRS 151493), d18O, dD, d13C, 
14C; MO0007MAJIONPH.005 
(DIRS 151517), C; 
GS980908312322.008 
(DIRS 145412), T, F, Sr2+, SiO2, 
HCO3
, and d34S 
H-1(Tcp) 47 572-6871 Tcp2 USW H-1 
H-1(Tcb) 48 
548727 4079926 YM-CR Yucca Mountain  Crest 
68718291 Tcb2 
DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930308312323.001 
(DIRS 145530), T, F, Sr2+ 
USW H-5 H-5 49 547668 4078841 YM-CR Yucca Mountain  Crest open borehole 
(7041220)1 
Tcb/Tct2 DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930308312323.001 
(DIRS 145530), T, F, Sr2+ 
USW SD-6 USW SD-6 50 547592 4077514 YM-CR Yucca Mountain  Crest open borehole 
(depth not 
reported) 
Not reported DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C; 
GS011108312322.006 
(DIRS 162911), d13C, d34S; 
GS010208312322.001 
(DIRS 162908), 
U-concentrations and isotopes 
USW H-3 H-3 51 547562 4075759 YM-CR Yucca Mountain  Crest open borehole 
(822-1220)1 
Tct2 DTNs: MO0007GNDWTRIS.009 
(DIRS 151509), d18O, dD, d13C, 
14C; MO0007MAJIONPH.011 
(DIRS 151524), C; 
MO0007MAJIONPH.012 
(DIRS 151529), C; 
GS920408312321.003 
(DIRS 105937), T, F, Sr2+ 
MDL-NBS-HS-000011 REV 02 A-19 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  Central 
USW G-4 G-4 52 548933 4078602 YM-C Yucca Mountain  
Central 
open borehole 
(541915)1 
Tct DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C); MO0007MAJIONPH.013 
(DIRS 151530), (C); 
GS930308312323.001 
(DIRS 145530), (T, F, Sr2+) 
b#1(Tcb) 53 863-8751 Tcb2 UE-25 b#1 
b#1(bh) 54 
549949 4078423 YM-C Yucca Mountain  
Central open borehole 
(470-1220)1 
Th/Tct2 
DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), (d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930308312323.001 
(DIRS 145530), T, F-, Sr2+ 
USW H-4 H-4 55 549188 4077309 YM-C Yucca Mountain  
Central 
open borehole 
(519-1220)1 
Tcb/Tct2 DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930308312323.001 
(DIRS 145530), T, F, Sr2+ 
UE-25 
UZ#16 
UZ#16 56 549484.9 4076986 YM-C Yucca Mountain  
Central 
490-492 Tcp DTN: MO0007MAJIONPH.007 
(DIRS 151519), C 
Yucca Mountain  Southeast 
UE-25 
ONC#1 
ONC#1 57 550479.9 4076608 YM-SE Yucca Mountain  
Southeast 
open borehole 
(433-469)15 
Th/Tcp15 DTN: MO0007MAJIONPH.004 
(DIRS 151516), C; Oliver and 
Root 1997 (DIRS 100069), Sr2+ 
and 87Sr/86Sr 
UE-25 c#1 c#1 58 550955 4075933 YM-SE Yucca Mountain  
Southeast 
open borehole 
(400914)1 
Tcb/Tct2 DTNs: MO0007GNDWTRIS.009 
(DIRS 151509), d18O, dD, d13C, 
14C; MO0007MAJIONPH.011 
(DIRS 151524), C; 
MO0007MAJIONPH.012 
(DIRS 151529), C; 
GS920408312321.003 
(DIRS 105937), T, F, Sr2+; 
LA0311EK831232.001 
(DIRS 166068), 87Sr/86Sr for c#1
MDL-NBS-HS-000011 REV 02 A-20 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  Southeast (Continued) 
c#3 59 DTNs: MO0007GNDWTRIS.009 
(DIRS 151509), d18O, dD, d13C, 
14C; MO0007MAJIONPH.011 
(DIRS 151524), C; 
MO0007MAJIONPH.012 
(DIRS 151529), C; 
GS920408312321.003 
(DIRS 105937), T, F, Sr2+ 
UE-25 c#3 
c#3(95-97) 60 
550930 4075902 YM-SE Yucca Mountain  
Southeast 
open borehole 
(402-913)1 
Tcb/Tct2 
DTNs: GS950808312322.001 
(DIRS 148114), C, d18O, dD; 
GS010808312322.004 (DIRS 
156007);GS010608315215.002 
(DIRS 156187); 
GS040208312322.003 
(DIRS 172396); 
U concentrations and isotopes; 
(DIRS 172396) 
GS980908312322.008 
(DIRS 145412), d34S; 
GS970708315215.008 
(DIRS 164674), 87Sr/86Sr for c#3 
UE-25 c#2 c#2 61 550955 4075871 YM-SE Yucca Mountain  
Southeast 
open borehole 
(401913)1 
Tcb2 DTNs: MO0007GNDWTRIS.009 
(DIRS 151509), d18O, dD, d13C, 
14C; MO0007MAJIONPH.011 
(DIRS 151524), C; 
MO0007MAJIONPH.012 
(DIRS 151529), C; 
GS920408312321.003 
(DIRS 105937), T, F, Sr2+; 
GS980908312322.008 
(DIRS 145412), d34S for c#2 
MDL-NBS-HS-000011 REV 02 A-21 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  Southeast (Continued) 
p#1(v) 62 381-11971 tuff2 UE-25 p#1 
p#1(c) 63 
551501 4075659 YM-SE Yucca Mountain  
Southeast 1297-18051 Srm/ 
DSlm2 
DTNs: MO0007GNDWTRIS.009 
(DIRS 151509), d18O, dD, d13C, 
14C; MO0007MAJIONPH.011 
(DIRS 151524), C; 
MO0007GNDWTRIS.008 
(DIRS 151508), d18O, dD, d13C, 
14C; MO0007MAJIONPH.010 
(DIRS 151523), C; 
GS930108315213.004 
(DIRS 145525), 
U concentrations and isotopes; 
GS920408312321.003 
(DIRS 105937), T, F, Sr2+; 
LA0311EK831232.001 
(DIRS 166068), 87Sr/86Sr 
USW WT-17 WT-17 64 549905 4073307 YM-SE Yucca Mountain  
Southeast 
open borehole 
(393-443)9 
Tcp9 DTNs: MO0007GNDWTRIS.003 
(DIRS 151493), d18O, dD, d13C, 
14C; MO0007MAJIONPH.005 
(DIRS 151517), C; 
GS980908312322.008 
(DIRS 145412), T, F, Sr2+, and 
d34S; GS980908312322.009 
(DIRS 118977), 
U concentrations and isotopes 
UE-25 WT#3 WT#3 65 552090 4072550 YM-SE Yucca Mountain  
Southeast 
open borehole 
(301-348)9 
Tcb9 DTNs: MO0007GNDWTRIS.003 
(DIRS 151493), d18O, dD, d13C, 
14C; MO0007MAJIONPH.005 
(DIRS 151517), C; 
GS980908312322.008 
(DIRS 145412), T, F, Sr2+, and 
d34S); GS980908312322.009 
(DIRS 118977), 
U concentrations and isotopes 
MDL-NBS-HS-000011 REV 02 A-22 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  Southeast (Continued) 
UE-25 
WT#12 
WT#12 66 550168 4070659 YM-SE Yucca Mountain  
Southeast 
open borehole 
(345-399)9 
Tpt/Tac9 DTNs: MO0007GNDWTRIS.007 
(DIRS 151497), d18O, dD, d13C, 
14C; MO0007GNDWTRIS.006 
(DIRS 151496), d18O, dD, d13C, 
14C; MO0008MAJIONPH.017 
(DIRS 151534), C; 
GS010608315215.002 
(DIRS 156187), U 
concentrations and isotopes; 
LA0311EK831232.001 
(DIRS 166068), 87Sr/86Sr; Oliver 
and Root 1997 (DIRS 100069), 
F, Sr2+ 
Jackass Flats 
UE-25 J-11 UE-25 J-11 67 563798 4071073 JF Jackass Flats open borehole 
(317-405)9 
Tb, Tpt9 DTNs: GS010308312322.003 
(DIRS 154734), pH, alkalinity, 
d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), ions; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
Crater Flat 
GEXA Well 4 GEXA Well 4 68 534069 4086110 CF Crater Flat (244-488)4 TV4,15 DTNs: GS970708312323.001 
(DIRS 145405), d18O, dD; 
MO0007MAJIONPH.008 
(DIRS 151521), C; 
GS980208312322.006 
(DIRS 146065), 
U concentrations and isotopes; 
Oliver and Root 1997 
(DIRS 100069), T, F, Sr2+, 
87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-23 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Crater Flat (Continued) 
USW VH-1 VH-1 69 539976 4071714 CF Crater Flat open borehole 
(184-762)1 
Tcb2 DTNs: MO0007GNDWTRIS.010 
(DIRS 151500), d18O, dD, d13C, 
14C; MO0007MAJIONPH.013 
(DIRS 151530), C; 
GS930308312323.001 
(DIRS 145530), T, F, Sr2+; 
LA0311EK831232.001 
(DIRS 166068), 87Sr/86Sr; Paces 
et al. 2002 (DIRS 158817), Table 
1, U concentrations and isotopes 
Crater Flat - Southwest 
USW-VH-2 VH-2 70 537738 4073214 CF-SW Crater Flat  Southwest open borehole 
(164-1219)15 
Tv15 DTNs: GS930108315213.002 
(DIRS 148109), C; 
GS970708312323.001 
(DIRS 145405), d18O, dD; 
MO0007MAJIONPH.008 
(DIRS 151521), C; 
GS930108315213.004 
(DIRS 145525), 
U concentrations and isotopes; 
LA0311EK831232.001 
(DIRS 166068), F, Sr2+, 
87Sr/86Sr 
NC-EWDP-7S NC-EWDP-7S 71 539558 4064318 CF-SW Crater Flat  Southwest (8.5-12.2)7 Paleospring 
deposits7 
DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S 
NC-EWDP- 
7SC 
NC-EWDP- 
7SC 
72 539558 4064320 CF-SW Crater Flat  Southwest Open borehole 
(7.6-237.3)7 
Paleospring 
deposits, 
Tertiary 
sediments 
and volcanic 
rock7 
DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S 
MDL-NBS-HS-000011 REV 02 A-24 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Crater Flat  Southwest (Continued) 
NC-EWDP- 
1DX 
NC-EWDP- 
1DX 
73 536768 4062503 CF-SW Crater Flat  Southwest Open borehole 
(16.8762)7 
Paleospring 
deposits, 
alluvium, 
Tertiary 
sediments7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
d18O, dD, d13C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), F, Sr2+; 
MO0007MAJIONPH.015 
(DIRS 151532), C; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
NC-EWDP- 
1DX Zone 2 
NC-EWDP- 
1DX Zone 2 
74 536768 4062503 CF-SW Crater Flat  Southwest (658.4682.8)7 Tertiary 
sediments7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP-1S 
Zone 1 
NC-EWDP-1S 
Zone 1 
75 536771 4062499 CF-SW Crater Flat  Southwest (48.8-54.9)7 Tertiary 
welded tuff7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-25 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Crater Flat  Southwest (Continued) 
NC-EWDP-1S 
Zone 2 
NC-EWDP-1S 
Zone 2 
76 536771 4062499 CF-SW Crater Flat  Southwest (64.082.3)7 Tertiary 
welded tuff7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP-1S NC-EWDP-1S 77 536771 4062499 CF-SW Crater Flat  Southwest Open borehole 
(15.8103.6) 
Tertiary 
welded tuff7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
d18O, dD, d13C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), ions; 
GS010208312322.001 
(DIRS 162908), 
U-concentrations and isotopes 
NC-EWDP- 
12PA 
NC-EWDP- 
12PA 
78 536906 4060766 CF-SW Crater Flat  Southwest (99.0-117.2)7 Tertiary 
Reworked 
tuff7 
DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
12PB 
NC-EWDP- 
12PB 
79 536863 4060794 CF-SW Crater Flat  Southwest (99.1117.3)7 Tertiary 
Reworked 
tuff7 
DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-26 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Crater Flat  Southwest (Continued) 
NC-EWDP- 
12PC 
NC-EWDP- 
12PC 
80 536872 4060809 CF-SW Crater Flat  Southwest (51.8-70.0)7 Alluvium7 DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
Yucca Mountain - South 
NC-EWDP- 
09SX 
NC-EWDP- 
09SX 
81 539039 4061004 YM-S Yucca Mountain  
South 
Open borehole 
(30.2-121.0) 
Valley fill, 
Alluvium, 
Tertiary 
volcanic 
rock7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
d18O, dD, d13C; 
GS011108312322.006 
(DIRS 162911), d13C, d34S; 
MO0007MAJIONPH.015 
(DIRS 151532), C; 
GS010308312322.002 
(DIRS 162910), F, Sr2+; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
09SX Zone 1 
NC-EWDP- 
09SX Zone 1 
82 539040 4061006 YM-S Yucca Mountain  
South 
(27.4-36.6)7 Alluvium7 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), 14C, d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-27 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  South (Continued) 
NC-EWDP- 
09SX Zone 2 
NC-EWDP- 
09SX Zone 2 
83 539040 4061006 YM-S Yucca Mountain  
South 
(42.7-48.8)7 Alluvium7 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
09SX Zone 3 
NC-EWDP- 
09SX Zone 3 
84 539040 4064006 YM-S Yucca Mountain  
South 
(76.288.4)7 Tertiary tuff7 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
09SX Zone 4 
NC-EWDP- 
09SX Zone 4 
85 539040 4061006 YM-S Yucca Mountain  
South 
(100.6-103.7)7 Tertiary tuff7 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-28 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  South (Continued) 
NC-EWDP- 
03D 
NC-EWDP- 
03D 
86 541273 4059444 YM-S Yucca Mountain  
South 
(159-292)7 Alluvium, 
Tertiary 
sedimentary 
and volcanic 
rocks7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), F, Sr2+; 
MO0007MAJIONPH.015 
(DIRS 151532), C; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
NC-EWDP-3S 
Zone 2 
NC-EWDP-3S 
Zone 2 
87 541273 4059444 YM-S Yucca Mountain  
South 
(103.6-128.0)14 Tertiary tuff 
and 
sediments7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP-3S 
Zone 3 
NC-EWDP-3S 
Zone 3 
88 541273 4059444 YM-S Yucca Mountain  
South 
(146.3-160.0)14 Tertiary tuff 
and 
sediments7 
DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d18O, d34S; 
GS010308312322.002 
(DIRS 162910), U concentration 
data; GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-29 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  South (Continued) 
CIND-R-LITE CIND-R-LITE 89 544027 4059809 YM-S Yucca Mountain  
South 
not reported Tv15 DTNs: GS930108315213.002 
(DIRS 148109), C; 
MO0007MAJIONPH.006 
(DIRS 151518), C; 
GS000700012847.001 
(DIRS 150842), C, I; 
GS930108315213.004 
(DIRS 145525), 
U concentrations and isotopes; 
LA0311EK831232.001 
(DIRS 166068), F, Sr2+, 
87Sr/86Sr 
NC-EWDP- 
15P 
NC-EWDP- 
15P 
90 544848 4058158 YM-S Yucca Mountain  
South 
(61.079.2)7 Alluvium7 DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
02D 
NC-EWDP- 
02D 
91 547744 40571647 YM-S Yucca Mountain  
South 
Open borehole 
(95.1493.2)7 
Alluvium7 DTNs: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010308312322.002 
(DIRS 162910), F, Sr2+; 
MO0007MAJIONPH.015 
(DIRS 151532), C; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
NC-EWDP- 
19D 
NC-EWDP- 
19D 
92 549238 4058265 YM-S Yucca Mountain  
South 
Open borehole 
(106.1443.9)7 
Alluvium, 
Tertiary tuff 
and 
sediments7 
DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions, 14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-30 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Yucca Mountain  South (Continued) 
NC-EWDP- 
19P 
NC-EWDP- 
19P 
93 549250 4058287 YM-S Yucca Mountain  
South 
(109.5139.8)7 Alluvium7 DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions, 14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
19D (alluvial) 
NC-EWDP- 
19D (alluvial) 
94 549238 4058265 YM-S Yucca Mountain  
South 
(125.9242.4) 
(assumed to be 
combined depth 
range of 
screened 
intervals 14) 
Alluvium7 DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions, 14C, 
d18O, dD, d13C, d34S 
NC-EWDP- 
19D (zone #1) 
NC-EWDP- 
19D (zone #1) 
95 549238 4058265 YM-S Yucca Mountain  
South 
(125.9131.4)7 Alluvium7 DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S 
NC-EWDP- 
19D (zone #2) 
NC-EWDP- 
19D (zone #2) 
96 549238 4058265 YM-S Yucca Mountain  
South 
(151.8157.3)7 Alluvium7 DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S 
NC-EWDP- 
19D (zone #3) 
NC-EWDP- 
19D (zone #3) 
97 549238 4058265 YM-S Yucca Mountain  
South 
(176.1206.0)7 Alluvium7 DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S 
NC-EWDP- 
19D (zone #4) 
NC-EWDP- 
19D (zone #4) 
98 549238 4058265 YM-S Yucca Mountain  
South 
(220.2242.4)7 Alluvium7 DTN: GS011108312322.006 
(DIRS 162911), T, pH, ions,14C, 
d18O, dD, d13C, d34S 
Amargosa Valley 
NC-EWDP- 
4PB 
NC-EWDP- 
4PB 
99 553202 4056768 LW Amargosa Valley (225.4-255.8)7 Alluvium7 DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions, 14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
4PA 
NC-EWDP- 
4PA 
100 553167 4056766 LW Amargosa Valley (123.5-147.9)7 Alluvium7 DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions, 14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-31 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa Valley (Continued) 
Desert Farms 
Garlic Plot 
Desert Farms 
Garlic Plot 
101 553295 4055305 LW Amargosa Valley open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
15S/50E-18ccc 15S/50E- 
18ccc 
103 553710 4055273 LW Amargosa Valley open borehole 
(105-102)2 
Qal2 DTN: MO0007MAJIONPH.006 
(DIRS 151518), C; Oliver and 
Root 1997 (DIRS 100069), F, 
Sr2+ 
NDOT NDOT 104 553685 4055242 LW Amargosa Valley open borehole 
(105-151) 
Qal13 DTN: MO0007MAJIONPH.008 
(DIRS 151521), C; 
MO0007MAJIONPH.009 
(DIRS 151522), C; 
GS940908315213.005 
(DIRS 164673), 
U concentrations and isotopes; 
Oliver and Root 1997 
(DIRS 100069), F and 87Sr/86Sr 
15S/50E-18cdc 15S/50E- 
18cdc 
105 553934.3 4055151 LW Amargosa Valley open borehole 
(105-120)2 
Qal2 DTN: MO0007MAJIONPH.006 
(DIRS 151518), C;Claassen 
1985 (DIRS 101125), Table 1, 
sample 34, T 
MDL-NBS-HS-000011 REV 02 A-32 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa Valley (Continued) 
Airport Well Airport Well 106 552846 4054904 LW Amargosa Valley open borehole 
(76-229)15 
Qal15 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, alkalinity); 
GS010308312322.003 
(DIRS 154734), ions, dD, d13C; 
GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS021008312322.002 
(DIRS 162913), d34S; Paces et 
al. 2002 (DIRS 158817), Table 1, 
U concentrations and isotopes 
15S/50E-19b1 15S/50E-19b1 107 553862.5 4054720 LW Amargosa Valley open borehole 
(103-110)15 
Qal13 DTN: MO0007MAJIONPH.006 
(DIRS 151518), C 
Amargosa River 
16S/48E-8ba 16S/48E-8ba 108 536979 4048129 AR Amargosa River open borehole 
(34-80)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 45 
16S/48E-7bba 16S/48E-7bba 109 534791 4048366 AR Amargosa River open borehole 
(0-38)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 46, T 
16S/48E-7cbc 16S/48E-7cbc 110 534546 4047441 AR Amargosa River open borehole 
(23-46)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 47, T 
16S/48E-18bcc 16S/48E- 
18bcc 
111 534827 4045747 AR Amargosa River open borehole 
(27-110)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
MDL-NBS-HS-000011 REV 02 A-33 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa River (Continued) 
16S/48E-17ccc 16S/48E- 
17ccc 
112 536122 4045106 AR Amargosa River open borehole 
(depth not 
reported) 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
16S/48E- 
18dad 
16S/48E- 
18dad 
113 536069 4045814 AR Amargosa River open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C; 
MO0007MAJIONPH.014 
(DIRS 151531), C 
16S/48E-8cda 16S/48E-8cda 114 537063 4045941 AR Amargosa River open borehole 
(40-unknown)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 51, T 
16S/48E- 
17abb 
16S/48E- 
17abb 
115 537035 4046681 AR Amargosa River open borehole 
(31-90)3 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 52, T 
Barrachman 
Dom/Irr. 
Barrachman 
Dom/Irr. 
116 534951 4048117 AR Amargosa River open borehole 
(depth not 
reported) 
Qal13 DTN: GS990808312322.001 
(DIRS 149393), d18O, dD, d13C; 
GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
MDL-NBS-HS-000011 REV 02 A-34 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa River (Continued) 
McCracken 
Domestic 
McCracken 
Domestic 
117 537372 4047061 AR Amargosa River open borehole 
(depth not 
reported) 
Qal13 DTN: GS990808312322.001 
(DIRS 149393), T, pH, alkalinity, 
d18O, dD, d13C; 
GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
Fortymile Wash - West 
16S/48E-15ba 16S/48E-15ba 118 539670 4046693 FMW-W Fortymile Wash  West open borehole 
(30-50)3 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 37, T 
16S/48E- 
10cba 
16S/48E- 
10cba 
119 539766 4047463 FMW-W Fortymile Wash  West open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 25, T 
16S/48E- 
15aaa 
16S/48E- 
15aaa 
120 540763 4046852 FMW-W Fortymile Wash  West open borehole 
(29-50)3 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 23, T 
MDL-NBS-HS-000011 REV 02 A-35 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  West (Continued) 
Selbach 
Domestic 
Selbach 
Domestic 
121 539256 4046506 FMW-W Fortymile Wash  West open borehole 
(depth not 
reported) 
Qal13 DTN: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/48E- 
15dda 
16S/48E- 
15dda 
122 540893 4045620 FMW-W Fortymile Wash  West open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
16S/49E- 
23add 
16S/49E- 
23add 
123 551958 4045217 FMW-W Fortymile Wash  West open borehole 
(depth not 
reported) 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C 
16S/48E- 
23bdb 
16S/48E- 
23bdb 
124 541469 4044729 FMW-W Fortymile Wash  West open borehole 
(29-100)3 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 24, T 
16S/48E-23da 16S/48E-23da 125 542391 4044729 FMW-W Fortymile Wash  West open borehole 
(24-100)3 
Qal13 DTN: MO0007MAJIONPH.006 
(DIRS 151518), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 53, T 
MDL-NBS-HS-000011 REV 02 A-36 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  West (Continued) 
Funeral 
Mountain 
Ranch Irrig 
Funeral 
Mountain 
Ranch Irrig 
126 541406 4043314 FMW-W Fortymile Wash  West open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
Fortymile Wash  South 
16S/49E-05acc 16S/49E- 
05acc 
127 546664.5 4049439 FMW-S Fortymile Wash  South open borehole 
(21-90)3 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C; Oliver and 
Root 1997 (DIRS 100069), F, 
Sr2+ 
16S/49E-8abb 16S/49E-8abb 128 546695 4048453 FMW-S Fortymile Wash  South open borehole 
(45-60)3 
Qtal3 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 5, T 
16S/49E-8acc 16S/49E-8acc 129 546723 4047806 FMW-S Fortymile Wash  South open borehole 
(45-60)3 
Qtal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 6, T 
MDL-NBS-HS-000011 REV 02 A-37 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  South (Continued) 
16S/49E-18dc 16S/49E-18dc 130 545144 4045579 FMW-S Fortymile Wash  South open borehole 
(33-110)3 
Qtal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C 
16S/48E- 
24aaa 
16S/48E- 
24aaa 
131 544077 4045235 FMW-S Fortymile Wash  South open borehole 
(29-150)3 
Qtal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 12, T 
16S/49E- 
19daa 
16S/49E- 
19daa 
132 545777 4044535 FMW-S Fortymile Wash  South open borehole 
(30-90)3 
Qtal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 11, T 
DeLee Large 
Irrigation 
DeLee Large 
Irrigation 
133 544975 4043727 FMW-S Fortymile Wash  South open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/48E-25aa 16S/48E-25aa 134 544160 4043602 FMW-S Fortymile Wash  South open borehole 
(26-50)3 
QTal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 13, T 
MDL-NBS-HS-000011 REV 02 A-38 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  South (Continued) 
16S/48E- 
36aaa 
16S/48E- 
36aaa 
135 544168 4042031 FMW-S Fortymile Wash  South open borehole 
(21-50)3 
Qal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C, 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 
MO0007MAJIONPH.014 
(DIRS 151531), C 
Bray Domestic Bray Domestic 136 546665 4040701 FMW-S Fortymile Wash  South open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
Amargosa 
Estates #2 
Amargosa 
Estates #2 
137 544634 4040394 FMW-S Fortymile Wash  South open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), pH, ions and 
14C; GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
17S/48E-1ab 17S/48E-1ab 138 544152 4040182 FMW-S Fortymile Wash  South open borehole 
(16-60)3 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C 
MDL-NBS-HS-000011 REV 02 A-39 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  South (Continued) 
17S/49E-7bb 17S/49E-7bb 139 544758 4038645 FMW-S Fortymile Wash  South open borehole 
(12-150)3 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 16, T 
17S/49E-8ddb 17S/49E-8ddb 140 547575 4037612 FMW-S Fortymile Wash  South open borehole 
(15-100)3 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, T 
17S/49E- 
35ddd 
17S/49E- 
35ddd 
141 552739 4031202 FMW-S Fortymile Wash  South 0.0 (Ash Tree 
Spring)3 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 20, T 
Fortymile Wash  East 
15S/49E-22a1 15S/49E-22a1 142 550086.3 4054974 FMW-E Fortymile Wash  East open borehole 
(90-174)15 
Qal15 DTN: MO0007MAJIONPH.006 
(DIRS 151518), C; Oliver and 
Root 1997 (DIRS 100069), F 
15S/49E-22dcc 15S/49E- 
22dcc 
143 549672.5 4053523 FMW-E Fortymile Wash  East open borehole 
(78-148)3 
Qal13 DTNs: MO0007MAJIONPH.006 
(DIRS 151518), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), I, Amargosa 
well 3; Oliver and Root 1997 
(DIRS 100069), F, Sr2+ 
MDL-NBS-HS-000011 REV 02 A-40 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  East (Continued) 
15S/49E-27acc 15S/49E- 
27acc 
144 549552.9 4052722 FMW-E Fortymile Wash  East open borehole 
(73-467)2 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Oliver and 
Root 1997 (DIRS 100069), F, 
Sr2+ 
O'Neill 
Domestic 
O'Neill 
Domestic 
145 547304 4047893 FMW-E Fortymile Wash  East open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/49E-9cda 16S/49E-9cda 146 548168 4047291 FMW-E Fortymile Wash  East open borehole 
(46-90)3 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 7, T 
16S/49E-9dcc 16S/49E-9dcc 147 548343 4047045 FMW-E Fortymile Wash  East open borehole 
(49-60)3 
Qal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 8, T 
16S/49E-16ccc 16S/49E- 
16ccc 
148 547508 4045222 FMW-E Fortymile Wash  East open borehole 
(depth not 
reported) 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C 
MDL-NBS-HS-000011 REV 02 A-41 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Fortymile Wash  East (Continued) 
Ponderosa 
Dairy #1 
Ponderosa 
Dairy #1 
149 549382 4038747 FMW-E Fortymile Wash  East open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
(U concentrations and isotopes 
17S/49E-9aa 17S/49E-9aa 150 549382 4038262 FMW-E Fortymile Wash  East open borehole 
(5-6)2 
Qal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD,14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C 
17S/49E- 
15bbd 
17S/49E- 
15bbd 
151 549843 4036855 FMW-E Fortymile Wash  East open borehole 
(17-110)3 
Qal13 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), 14C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 19, T 
M. Gilgan Well M. Gilgan Well 152 549550 4036791 FMW-E Fortymile Wash  East open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
17S/49E-15bc 17S/49E-15bc 153 549870 4036577 FMW-E Fortymile Wash  East open borehole 
(15-157)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 38, T 
MDL-NBS-HS-000011 REV 02 A-42 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Gravity Fault 
NC-EWDP-5S NC-EWDP-5S 154 555676 4058229 GF Gravity fault (183.3-237.7)7 Alluvium7 DTNs: GS010308312322.003 
(DIRS 154734), T, d18O, dD; 
GS010308312322.002 
(DIRS 162910), F, Sr2+, SiO2; 
MO0007MAJIONPH.015 
(DIRS 151532), pH, C; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
NC-EWDP- 
5SB 
NC-EWDP- 
5SB 
155 555678 4058216 GF Gravity fault (115.6-149.0)7 Alluvium7 DTNs: GS011108312322.006 
(DIRS 162911), T, pH, ions, 14C, 
d18O, dD, d13C, d34S; 
LA0311EK831232.002 (DIRS 
166069), 87Sr/86Sr 
16S/50E-7bcd 16S/50E-7bcd 156 553932 4047540 GF Gravity fault open borehole 
(43-60)3 
Qal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C 
Nelson 
Domestic 
Nelson 
Domestic 
157 553683 4047702 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/49E- 
12ddd 
16S/49E- 
12ddd 
158 553834 4047386 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
MDL-NBS-HS-000011 REV 02 A-43 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Gravity Fault (Continued) 
Lowe Domestic Lowe 
Domestic 
159 552116 4047002 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/49E- 
15aaa 
16S/49E- 
15aaa 
160 550556 4046842 GF Gravity fault open borehole 
(51-120)3 
Qal2 DTNs: MO0007MAJIONPH.012 
(DIRS 151529), C; 
MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C; 
MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 29, T 
Anvil Ranch 
Irrigation 
Anvil Ranch 
Irrigation 
161 548906 4043723 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/49E- 
36aaa 
16S/49E- 
36aaa 
162 553569 4042053 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: MO0007GNDWTRIS.011 
(DIRS 151501), d18O, dD, d13C, 
14C; MO0007MAJIONPH.014 
(DIRS 151531), C 
16S/49E- 
35baa 
16S/49E- 
35baa 
163 551307 4042040 GF Gravity fault open borehole 
(26-100)3 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 33, T 
MDL-NBS-HS-000011 REV 02 A-44 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Gravity Fault (Continued) 
Payton 
Domestic 
Payton 
Domestic 
164 553134 4041977 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
16S/49E- 
36aba 
16S/49E- 
36aba 
165 553222 4041836 GF Gravity fault open borehole 
(depth not 
reported) 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
16S/49E- 
35aaa 
16S/49E- 
35aaa 
166 551980 4041520 GF Gravity fault open borehole 
(35-52)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
Oettinger Well Oettinger Well 167 551698 4040954 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
Amargosa 
Motel (b) 
Amargosa 
Motel (b) 
168 551720 4038945 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
MDL-NBS-HS-000011 REV 02 A-45 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Gravity Fault (Continued) 
17S/49E-11ba 17S/49E-11ba 169 551873 4038623 GF Gravity fault open borehole 
(20-56)2 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 36, T 
Spring 
Meadows Well 
#8 
Spring 
Meadows Well 
#8 
170 560913 4038129 GF Gravity fault open borehole 
(depth not 
reported) 
Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 10/15/70 sample 
17S/50E- 
19aab 
17S/50E- 
19aab 
171 555998 4035691 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 58, T 
USFWS - Five 
Springs Well 
USFWS - Five 
Springs Well 
172 561126 4035571 GF Gravity fault open borehole 
(depth not 
reported) 
Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 8/24/90, 
4/28/92, 8/18/92, and 9/22/96 
samples; the 1990 and 1992 
samples are also in DTN: 
GS931100121347.007 
(DIRS 149611) 
Spring 
Meadows Well 
#10 
Spring 
Meadows Well 
#10 
173 556916 4034042 GF Gravity fault open borehole 
(depth not 
reported) 
Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 8/15/62 sample 
18S/49E-1aba 18S/49E-1aba 174 554035 4031056 GF Gravity fault 0 (Spring)3 Qal13 DTN: MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 40, T 
18S/50E-6dac 18S/50E-6dac 175 556035 4029960 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
18S/50E-7aa 18S/50E-7aa 176 556040 4029158 GF Gravity fault open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.014 
(DIRS 151531), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 59, T 
MDL-NBS-HS-000011 REV 02 A-46 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa River/ Fortymile Wash 
16S/48E-36dcc 16S/48E- 
36dcc 
177 543530 4040395 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(13-120)3 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 26, T 
Crane 
Domestic 
Crane 
Domestic 
178 543587 4037930 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(depth not 
reported) 
Qal13 DTNS: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
27N/4E-27bbb 27N/4E-27bbb 179 541520 4034130 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(14-90)3 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 54, T 
IMV on 
Windjammer 
IMV on 
Windjammer 
180 548115 4033603 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
17S/49E-29acc 17S/49E- 
29acc 
181 547349 4033420 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 44, T 
17S/49E- 
28bcd 
17S/49E- 
28bcd 
182 548370 4033395 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C 
MDL-NBS-HS-000011 REV 02 A-47 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa River/ Fortymile Wash (Continued) 
18S/49E-2cbc 18S/49E-2cbc 183 551377 4030023 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(22-160)3 
Qal2 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 41, T 
Mom's Place Mom's Place 184 551996 4029417 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(depth not 
reported) 
Qal13 DTNs: GS990808312322.001 
(DIRS 149393), T, pH, d18O, dD, 
d13C; GS990808312322.002 
(DIRS 162917), ions and 14C; 
GS021008312322.002 
(DIRS 162913), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes 
18S/49E- 
11bbb 
18S/49E- 
11bbb 
185 551307 4029283 AR/FMW Amargosa River/ 
Fortymile Wash 
open borehole 
(depth not 
reported) 
Qal13 DTN: MO0007MAJIONPH.012 
(DIRS 151529), C; Claassen 
1985 (DIRS 101125), Table 1, 
sample 42, T 
Skeleton Hills 
TW-5 TW-5 186 562604 4054686 SH Skeleton Hills open borehole 
(207-244)15 
Protozoic 
clastic 
rocks16 
DTNs: MO0007MAJIONPH.006 
(DIRS 151518), C; 
MO0007GNDWTRIS.004 
(DIRS 151494), d18O, dD; 
MO0007MAJIONPH.002 
(DIRS 151507), C; Oliver and 
Root 1997 (DIRS 100069), F, 
Sr2+, 87Sr/86Sr 
Unnamed Well 
15S/50E-22-7 
Unnamed Well 
15S/50E-22-7 
187 559605 4053895 SH Skeleton Hills open borehole 
(depth not 
reported) 
Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 11/20/72 sample
MDL-NBS-HS-000011 REV 02 A-48 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Amargosa Flat 
Amargosa 
Tracer Hole #2 
Amargosa 
Tracer Hole 
#2 
188 569158 4043531 AF Amargosa Flat open borehole 
(12-252)2 
Paleozoic 
carbonate 
rocks2 
DTN: LA0311EK831232.001 
(DIRS 166068), 9/17/66, 
10/7/67, 2/15/88 and 2/16/68 
samples 
Cherry Patch 
Well, 17S/52E- 
08cdb 
Cherry Patch 
Well, 
17S/52E- 
08cdb 
189 576207 4038588 AF Amargosa Flat open borehole 
(10-122)2 
Qal 
(limestone)2 
DTN: LA0311EK831232.001 
(DIRS 166068), 8/24/90, 
3/24/92, 9/5/91,and 5/15/97 
samples; the 1990 through 1992 
data are also in 
DTN: GS931100121347.007 
(DIRS 149611) 
USDOE-MSHC 
shallow Well 
USDOE-MSHC 
shallow Well 
190 565396 4039700 AF Amargosa Flat open borehole 
(depth not 
reported) 
Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 9/27/96 sample 
Mine Mountain 
UE-17a UE-17a 191 574116 4103157 MM Mine Mountain Bailed from 254 
Open borehole 
(194-354)6 
Not reported DTN: LA0311EK831232.001 
(DIRS 166068), 6/9/93 sample; 
also in Rose et al. 1997 
(DIRS 144725), samples 5658 
UE-1a UE-1a 192 578395 4100387 MM Mine Mountain Bailed from 168 
Open borehole 
(167-171)6 
Tv5 DTN: LA0311EK831232.001 
(DIRS 166068), 9/1/92 sample; 
also in Davisson et al. 1994 
(DIRS 162939); Rose et al. 1997 
(DIRS 144725), sample 46 
UE-1b UE-1b 193 579004 4100389 MM Mine Mountain Bailed from 207 
Open borehole 
(198-382)6 
Paleozoic 
carbonate 
rocks5 
DTN: LA0311EK831232.001 
(DIRS 166068), 9/1/92 sample; 
also in Davisson et al. 1994 
(DIRS 162939); Rose et al. 1997 
(DIRS 144725), sample 45 
UE-16f UE-16f 194 574100 4098960 MM Mine Mountain Bailed from 395 
Open borehole 
(112-422)6 
Eleana Fm.5 DTN: LA0311EK831232.001 
(DIRS 166068), 7/12/93; Rose et 
al. 1997 (DIRS 144725), 
sample 42, sulfate, SO4
2- and 
Na+ 
MDL-NBS-HS-000011 REV 02 A-49 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Mine Mountain (Continued) 
UE-14b UE-14b 195 575427 4087304 MM Mine Mountain Not reported Tv5 DTN: LA0311EK831232.001 
(DIRS 166068), 9/1/88 and 
7/24/91 samples; the 9/1/88 
sample is in Chapman and Lyles 
1993 (DIRS 162940), p 39 
Pluto 1 Pluto 1 196 579238 4075338 MM Mine Mountain Possibly 
perched5 
Tv5 DTN: LA0311EK831232.001 
(DIRS 166068), 11/2/84 sample; 
also in Chapman and Lyles 1993 
(DIRS 162940), p. 38 
Pluto 5 Pluto 5 197 579263 4074977 MM Mine Mountain Possibly 
perched5 
Tv5 DTN: LA0311EK831232.001 
(DIRS 166068), 9/26/88 sample; 
also in Chapman and Lyles 1993 
(DIRS 162940), p. 38. 
USGS Test 
Well F (HTH) 
USGS Test 
Well F (HTH) 
198 578858 4068348 MM Mine Mountain Not reported Tv5 DTN: LA0311EK831232.001 
(DIRS 166068), 5/21/75,2/2/76, 
and 3/12/80 samples 
Funeral Mountains 
Woodcamp 
Spring 
Woodcamp 
Spring 
199 502027 4091249 FMt Funeral Mountains 0.0 (spring 
discharge)12 
Tertiary 
volcanic 
rock12 
DTN: GS960408312323.002 
(DIRS 162915), C, I 
Bond Gold 
Mining #13 
Bond Gold 
Mining #13 
200 519383 4059841 FMt Funeral Mountains open borehole 
(depth not 
reported) 
Qal13 DTN: GS010308312322.003 
(DIRS 154734), T, pH, alkalinity, 
ions, d18O, dD, d13C, 14C; 
GS011108312322.006 
(DIRS 162911), d34S; 
GS010208312322.001 
(DIRS 162908), 
U concentrations and isotopes; 
GS010308312322.002 
(DIRS 162910), 
U concentrations); 
LA0311EK831232.002 
(DIRS 166069), 87Sr/86Sr 
MDL-NBS-HS-000011 REV 02 A-50 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A4-3. Summary of Groundwater Wells and Data Sources (Continued) 
Well Identifier 
Abbreviation 
Used in 
Appendix 
Figure 
A6-5 
UTM-Xa 
(m) 
UTM-Y3 
(m) Areab 
Approximate 
Interval 
Sampled (m)e 
Geologic 
Unitc,e 
Reference for Sampled Depth 
and Chemical (C) and Isotopic 
(I) Datad 
Funeral Mountains (Continued) 
Nevares 
Spring 
Nevares 
Spring 
201 516068 516068 FMt Funeral Mountains 0.0 (spring 
discharge)12 
Travertine12 DTN: GS960408312323.002 
(DIRS 162915), C, I 
Travertine 
Spring 
Travertine 
Spring 
202 515211 4032657 FMt Funeral Mountains 0.0 (spring 
discharge)12 
Qal12 DTN: GS960408312323.002 
(DIRS 162915), C, I 
a Coordinate data are from (1) LA0311EK831232.001 (DIRS 166068), , (2) GS010908312332.002 (DIRS 163555), (3) GS010208312322.001 (DIRS 162908), , (4) 
Paces et al. (2002 [DIRS 158817]), (5) GS010808312322.004 (DIRS 156007), , and (6) LA0309EK831223.001 (DIRS 165471). These sources do not always 
identify whether coordinates are reported relative to North American Datum (NAD) 1927 or 1983, and the coordinates listed may represent a mixture of both 
coordinate systems. Because of uncertainty in the reference system used in any source, an uncertainty of approximately 100 m results in the coordinates of 
boreholes listed. Because of the scale at which data are presented, this uncertainty has a negligible effect on the interpretation of groundwater geochemical 
patterns and flow paths given in this appendix. 
b See Figure A6-5 and Section A6.7.2 for a definition of subareas near Yucca Mountain. The subareas used in this appendix may differ from subareas used in 
DTNs that begin MO000, which are associated with the earlier analysis model report version of this appendix. 
c Geologic 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 Tertiary Calico Hills Formation; Tcb Tertiary Bullfrog Member of 
Crater Flat tuff; Tcp Tertiary Prow Pass Member of Crater Flat tuff; Tlr Tertiary Lithic Ridge tuff; DSlm Devonian and Silurian Lone Mountain Dolomite; Srm Silurian 
Roberts Mountain Dolomite; Tfb (and its subunits Tfbr and Tfbw) are volcanic rocks of the Tertiary Beatty Wash Formation; Tm is the Tertiary Timber Mountain tuff; 
Tma (and its subunits Tmaw, Tmap and Tmar) are the Tertiary Ammonia Tanks tuff; Tft is a basalt; and Ttc is the Tertiary commendite of Ribbon Cliff). Geologic 
units are defined in (Oliver and Root 1997 [DIRS 100069], p. 5; Buesch et al. 1996 [DIRS 100106], Table 4; McKinley et al. 1991 [DIRS 116222], p. 5-6; Day et al. 
1998 [DIRS 101557], map sheet 2; Slate et al. (1999 [DIRS 150228]). Also, see stratigraphic column in Figure A6-2. 
d C: 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 [DIRS 101125], Table 1) provide traceability between identifiers used in the listed DTNs and those listed in column 1 of this table. 
e Sources of data on interval depths and geologic units sampled are (1) Benson and McKinley (1985, [DIRS 101036], Table 1), (2) McKinley et al. (1991 
[DIRS 116222], Tables 1 and 5), (3) Claassen (1985 [DIRS 101125], Table 1), (4) Rose et al. (2002 [DIRS 162938], Table A-1), (5) Chapman and Lyles (1993 
[DIRS 162940], Figures. 11, 13, 16), (6) Davisson et al. (1994 [DIRS 162939], Table 1), (7) LA0311EK831223.001 (8) Robledo et al. (1998 [DIRS 165986], 
Tables 1 and 4), (9) Graves et al. (1998 [DIRS 155411], throughout report), (10) OBrien (1998 [DIRS 101278], Table 2), (11) DTN GS980908312322.008 
(DIRS 145412), , (12) Steinkampf and Werrell (2001 [DIRS 158818], pp. 11 to 14), (13) lithology estimated from Figure 1 of Claassen (1985 [DIRS 101125]), 
(14) GS010308312322.003 (DIRS 154734), , (15) Oliver and Root (1997 [DIRS 100069], yucca.xls), (16) Winograd and Thordarson (1975, [DIRS 101167], Plate 1) 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-51 November 2004 
A5. ASSUMPTIONS 
The scientific analyses presented in this appendix sometimes required that assumptions be made 
about 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. 
Table A5-1. Assumptions 
Assumption Rationale for Assumption 
1 To provide an initial assessment 
of flow directions indicated by 
the hydraulic gradient in Figure 
A6-3, flow vectors are drawn 
parallel to this gradient, implicitly 
assuming the hydraulic 
conductivity of the rocks is 
isotropic. 
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 initial 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. This assumption does not influence the 
conclusions herein that are based solely on groundwater geochemical 
and isotopic data. 
2 The dissolved aluminum 
concentration of groundwater in 
the Yucca Mountain area is in 
equilibrium with kaolinite. 
The assumption that groundwater aluminum concentrations are 
controlled by equilibrium with kaolinite was supported by calculating 
dissolved aluminum concentrations in equilibrium with a variety of 
secondary minerals with PHREEQC (Parkhurst and Appelo 1999 
[DIRS 159511]) and comparing these calculated concentrations with 
concentrations measured at a subset of wells in the Yucca Mountain 
area (Figure A6-30). This assumption affects calculation of mineral 
saturation indices in Table A6.3-5. 
3 For the purpose of calculating 
mineral saturation indices, the 
temperature of groundwater 
samples can be approximated 
either from published maps of 
water table temperatures at 
Yucca Mountain, or, in the 
Amargosa Desert, can be 
assumed to be 25C. 
The use of a contour map of water table temperatures (Fridrich et al. 
1994 [DIRS 100575], Figure 8) to estimate groundwater sample 
temperatures at Yucca Mountain is an acceptable approximation 
because most of the samples for which this approximation was made 
are from the upper part of the saturated zone (Figure A6-2 samples 33, 
34, 41, 56, 57, and 66). Likewise, the assumption that groundwater 
samples in the Amargosa Desert with no measured temperatures are at 
25C is an acceptable approximation because most of the measured 
groundwater sample temperatures are in the range of 20C to 30C (see 
data for the LW, FMW-S, FMW-E, FMW-W, GF, AR, and AR/FMW 
sample groups in Table A6-1. 
4 The chemical and isotopic 
composition of the groundwater 
sample from the carbonate 
aquifer at borehole p#1 (sample 
p#1(c) in Tables A6-1 and A6-2) 
and, in particular, its Cl and 
SO4
2 concentrations, 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 and SO4
2 concentrations 
of groundwater at p#1 (28 and 160 mg/L, respectively) are similar to the 
concentrations of these ions in groundwater from the carbonate aquifer 
at Ash Meadows where Cl ranges from 21 to 27 mg/L and SO4
2 ranges 
from 80 to 111 mg/L (Winograd and Pearson 1976 [DIRS 108882], 
Table 1). The variability in the concentrations of Cl and SO4
2 in the 
carbonate aquifer at Ash Meadows may indicate the extent of the 
variability that could be expected at Yucca Mountain. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-52 November 2004 
Table A5-1. Assumptions (Continued) 
Assumption Rationale for Assumption 
5 The chloride mass-balance 
(CMB) method is assumed to be 
applicable to the estimation of 
recharge rates at Yucca 
Mountain. The CMB method 
assumes one-dimensional, 
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 chloride-bearing minerals in the soils and rocks at 
Yucca Mountain. The departures of actual flow conditions from the 
assumption of one-dimensional piston flow are mitigated somewhat for 
the calculations done on the basis of the saturated-zone chloride data. 
This result 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 nonpiston flow are mitigated 
because hydrodynamic mixing and mixing in the well bore when 
groundwater is pumped tend to average the Cl concentrations of fastand 
slow-moving water percolating through fractures and matrix in the 
unsaturated zone. Run-on and runoff both can redistribute Cl 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 Cl balance for Yucca Mountain itself is 
not affected by this process. Runoff from Yucca Mountain to Fortymile 
Wash would tend to cause the actual Cl-deposition rates at Yucca 
Mountain to be less than those assumed in the calculations and, thus, 
cause the estimated Yucca Mountain recharge to overestimate the 
actual recharge. 
6 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. 
Several independent lines of evidence support this assumption. First, 
the range of deposition rates assumed for Yucca Mountain reflect the 
present-day wet and dry chloride deposition rates estimated for sites at 
Red Rock Canyon and Kawich Range, Nevada (BSC 2002 
[DIRS 160247]), 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 
[DIRS 107034]). Finally, the nearly uniform Cl concentrations in the 
perched water and SZ groundwater beneath Yucca Mountain also 
support the assumption. Section A6.3.6.5 addresses the uncertainty in 
the deposition rate and propagation of that uncertainty through the 
resulting estimates of recharge obtained by the chloride mass-balance 
method. 
7 The chemical and isotopic 
composition of deep-perched 
water from boreholes UZ-14 and 
SD-7 is representative of local 
recharge at Yucca Mountain. 
A possible conceptual model for the formation of perched water at Yucca 
Mountain is that perched water originates when local infiltration rates 
exceed the hydraulic conductivity of the perching layer, so that deep 
infiltration begins to pond at the top of the layer. The perched water then 
moves toward the water table to become recharge either by (1) seeping 
slowly through the matrix of the perching layer, (2) moving laterally 
down-dip along the top of the perching layer, or (3) by draining down 
faults where these intersect the perching layer, depending on local 
structural conditions. Although some additional water/rock interactions 
such as cation exchange may occur in the deep UZ between the surface 
and perched-water horizons, the deep perched water already 
incorporates the effects of evaporative processes and water/rock/gas 
interactions in the soil zone that dominate the chemical and isotopic 
compositions of unsaturated-zone waters (Meijer 2002 [DIRS 158813]). 
The compositions of the deep-perched waters are therefore a good 
approximation of the water compositions of local recharge. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-53 November 2004 
Table A5-1. Assumptions (Continued) 
Assumption Rationale for Assumption 
8 Carbon isotope exchange is not 
a significant process affecting 
14C activities of groundwater 
near Yucca Mountain. 
The age-correction models (Section A6.3.6.6.2) did not consider the 
process of carbon-isotope exchange, a process that alters the carbonisotope 
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 age corrections were made were under saturated 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 modeling. 
9 The d13C of calcite in alluvium is 
similar to the d13C of pedogenic 
calcite in the unsaturated zone of 
Yucca Mountain (about 4 per 
mil). 
No data presently exists on the isotopic composition of calcite contained 
in alluvium south and southeast of the repository area at Yucca 
Mountain. Late-stage fracture-lining calcite from the unsaturated zone 
has a distribution with a mode of about 6 per mil, whereas 
intermediate-stage calcite is more uniformly distributed and has a mode 
of about 2 per mil (Whelan et al. 1998 [DIRS 108865, p. 179). An 
average value of 4 per mil approximates an average value for the 
intermediate and late-stage fracture-lining calcite in the unsaturated 
zone at Yucca Mountain. 
10 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, and 
d34S are sufficiently conservative 
(i.e., nonreactive) to identify 
likely flow paths and 
groundwater mixing 
relationships. 
This assumption is sound for dD and d18O because these constitute the 
water molecule; thus, large amounts of water/rock interaction are 
required to alter their composition. This assumption is acknowledged in 
the text as an approximation for Cl and SO4
2. Changes in the input 
concentrations of these constituents as a result of climate change or 
modifications due to water/rock interaction will result in variability along a 
flow path. However, in most cases, this effect is expected to be small. 
Regardless, the areal contrast in concentrations between these 
constituents is large enough that meaningful inferences about flow 
directions can be made. 
11 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. 
12 A straight-line distance was 
assumed in evaluating transport 
times between wells based on 
14C. 
The straight-line distance assumption allows for straightforward 
calculation of transport times and results in the fastest transport time. It 
is therefore a conservative assumption. 
13 No correction was made to 
estimated 14C transport times in 
fractured volcanics for matrix 
diffusion. 
Corrections for diffusion of 14C into the matrix of fractured volcanics 
would tend to increase the calculated groundwater transport times 
because the matrix pore waters tend to have lower pmc values. 
However, detailed data on the 14C content of pore waters along potential 
pathways are lacking. 
14 No additional 14C is added to 
groundwater from downgradient 
recharge as a groundwater 
moves from an upgradient to a 
downgradient well defining a 
flow-path segment. 
The data on oxygen and hydrogen isotopes for groundwater sampled in 
downgradient wells generally indicate lighter isotope ratios as water is 
sampled from wells progressively further downgradient. The lighter 
isotope ratios represent older waters (Pleistocene). The lack of modern 
hydrogen and oxygen isotope ratios in downgradient locations is 
evidence of minimal modern recharge at these locations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-54 November 2004 
A.6. SCIENTIFIC ANALYSIS 
A6.1 OBJECTIVES 
The objective 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. An analysis of these processes based on geochemical data can 
provide an independent basis for evaluating the interpretation of the flow system provided by the 
SZ site-scale flow model. 
The analysis is structured as follows: Section A6.2 provides background information regarding 
geographic, geologic and hydrologic setting as well as a summary of over twenty five years of 
geologic and hydrologic research that has taken place in the region. Information within these 
sections is continually used and evaluated throughout this appendix. Sections A6.3.1 through 
A6.3.5 provide an overview of the hydrochemical setting in the study area. A discussion of 
hydrochemical trends with depth for some boreholes provided in Section A6.3.3, areal 
distribution plots of hydrochemical and isotopic data discussed in Section A6.3.4, and calculated 
geochemical parameters presented in Section A6.3.5 provide the initial hydrochemical 
framework for evaluating the hydraulic system. Particular attention is provided in 
Section A6.3.6 to evaluate the sources and evolution of water beneath Yucca Mountain. 
Sections A6.3.7 through A6.3.10 then evaluate flow away from Yucca Mountain. 
Section A6.3.7 evaluates mixing patterns evident in some areas, and Section A6.3.8 describes 
PHREEQC models of groundwater mixing and evolution. Section A6.3.9 uses 14C groundwater 
ages to evaluate flow velocities, and Section A6.3.10 confirms the consistency of flow models 
using FEHM and flow models derived from hydrochemical arguments. Finally, Section A6.3.11 
integrates all the above sections to produce a map describing regional flow pathways. 
A6.2 INTRODUCTION AND PREVIOUS WORK 
A6.2.1 Geography, Geology, and Physical Hydrology 
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 in the vicinity of Timber 
Mountain (Sawyer et al. 1994 [DIRS 100075], Figure 1). Volcanic rocks erupted from these 
calderas typically thin to the south and eventually pinch out beneath alluvium in the Amargosa 
Desert (Figure A6-1). Yucca Mountain itself extends southward from Pinnacles Ridge toward 
the Amargosa Desert (Figure A6-1). Volcanic units on Yucca Mountain typically dip 5 to 
10 degrees to the east. 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 [DIRS 101557], pp. 6 and 7). Underlying Crater Flat is a thick sequence of 
alluvium, lava, and tuff 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 also underlain by 
a thick sequence of alluvium and volcanic rocks. Timber Mountain, approximately 25 km to the 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-55 November 2004 
north of the repository area, is a resurgent dome within the larger caldera complex that erupted 
the tuffs at Yucca Mountain. 
The central block of Yucca Mountain 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 A6-1). Topography north of the central block at Yucca Mountain 
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. 
Based on similarities in their core-scale hydrologic and mechanical properties, saturated volcanic 
units at Yucca Mountain were grouped into two confining layers and two aquifers by 
Luckey et al. (1996 [DIRS 100465], pp. 17 to 19) (Figure A6-2). Figure A6-2 represents a 
simplification of the more detailed hydrostratigraphic framework presented in Hydrogeologic 
Framework Model for the Saturated-Zone Site-Scale Flow and Transport Model 
ANL-NBS-HS-000033 (BSC 2004 [DIRS 170008]) that is used in the SZ site-scale flow model, 
(Table 6-17) and is used here only to provide a broad overview of the site hydrostratigraphy. 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 formation 
took place before approximately 11 Ma (Broxton et al. 1987 [DIRS 102004], p. 101; Bish 1989 
[DIRS 101194], pp. 31, 33) and was concentrated in the originally permeable, nonwelded vitric 
tuffs; zeolitization 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. Zeolitization 
and clay alteration is more intense and zeolite facies alteration occurs higher in the section in 
northern Yucca Mountain because of the high paleotemperature gradients that existed near the 
calderas (Broxton et al. 1987 [DIRS 102004], pp 107 to 108; Bish 1989 [DIRS 101194], p. 35). 
Regionally, argillite of the Eleana Formation is a confining layer, and the Paleozoic carbonate 
rocks are an important aquifer (Winograd and Thordarson 1975 [DIRS 101167], Table 1, 
columns 6, 7; Laczniak et al. 1996 [DIRS 103012], Table 1). The Eleana Formation is inferred 
to be present in northern Yucca Mountain based on areal magnetic data (Luckey et al. 1996 
[DIRS 100465], p. 20), though it has not been penetrated by drill core. The carbonate aquifer 
was penetrated at borehole p#1 (the correspondence between well identifiers and borehole 
abbreviations is given in Table A4-3), but its continuity and thickness in this part of southern 
Nevada, and consequently its importance as a regional aquifer, is thought to be less near 
Yucca Mountain than in areas farther to the east (Thomas et al. 1996 [DIRS 101933], 
Figure 17). 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-56 November 2004 
DTN: GS991208314221.001 [DIRS 145263] (Tertiary faults). 
NOTE: The solid rectangle is the boundary of the SZ site-scale flow and transport model. UTM=Universal Transverse Mercator. 
Figure A6-1. Important Physiographic Features near Yucca Mountain 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-57 November 2004 
Source: Luckey et al. (1996 [DIRS 100465]), Figure 7. 
NOTE: Valley Fill of variable age, consisting of sands, gravels, clays, freshwater limestones, and basaltic lavas, 
overlies various units of the Tertiary volcanic rocks and pre-Tertiary rocks in basins to the west, east, and 
south of Yucca Mountain. For example, see Kilroy (1991 [DIRS 103010], Figure 3). 
Figure A6-2. Selected Geologic and Hydrogeologic Units for the Saturated Zone at Yucca Mountain 
A map of the potentiometric surface in the Yucca Mountain area was developed as part of an 
associated analysis report (USGS 2001[DIRS 154625], Figure 1-2) based on average 
waterlevel data collected from 1985 to 1995 (Figure A6-3). 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. (USGS 2001 [DIRS 154625], p. 18). The water levels have been influenced by 
local pumping in the southern part of the model area (USGS 2001 [DIRS 154625], p. 23). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-58 November 2004 
DTN: GS991208314221.001 [DIRS 145263] (Tertiary faults); GS00050812332.0001 [DIRS 149947] 
(Water-level contours) 
Source: USGS (2001 [DIRS 154625], Figure 1-2) 
NOTE: The inferred groundwater flow directions are based on Assumption 1 in Table A5-1. The circular areas outlined 
in red near the Calico Hills in the northeast corner of the map are zones of hydrothermal alteration associated 
with granitic intrusions (Table 6-17). The semicircular area along the central northern portion of the map is the 
southern boundary of the Claim Canyon caldera (Table 6-17). The other red lines are selected faults; blue 
crosses indicated the location of hydraulic head measurements. Blue lines are contours showing elevation (in 
meters above sea level) of the potentiometric surface; contour intervals vary. UTM=Universal Transverse 
Mercator. 
Figure A6-3. Potentiometric Surface and Inferred Flow Directions (light blue arrows) for Yucca Mountain 
and Vicinity 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-59 November 2004 
Several possible flow directions were defined by drawing arrows parallel to the gradient in the 
potentiometric surface (Figure A6-3). The flow directions were drawn under the assumption that 
hydraulic conductivity and transmissivity are isotropic (Assumption 1 in Table A5-1). In 
fractured-rock aquifers, such as those at Yucca Mountain, hydraulic conductivity probably is 
anisotropic (Luckey et al. 1996 [DIRS 100465], p. 36). Nonetheless, this assumption provides a 
starting point for evaluating the possible flow pathways 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 from Figure A6-3. 
The flow paths shown in Figure A6-3 indicate that water may flow from the north and northwest 
under Yucca Mountain. In Figure A6-3, some of the flow from the north is predicted to flow 
southeastward toward Fortymile Wash in northern Yucca Mountain, an area dominated by 
northwest-trending, fault-controlled washes. The inferred flow directions 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 A6-3). The faults in the southern part of Yucca Mountain do not seem 
to exert an observable effect on the potentiometric surface, but this may reflect the sparseness of 
boreholes and small hydraulic gradient in this area. 
A6.2.2 Previous Hydrochemical Investigations 
Yucca Mountain has been under investigation as a repository site since the early 1980s, and an 
extensive body of literature exists concerning its groundwater hydrochemical and isotopic 
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. Literature data were used to create and evaluate conceptual models, corroborate 
existing models, and to enhance the database of hydrochemistry data obtained by the Project. 
Several published studies (White and Chuma 1987 [DIRS 108871]; Benson and Klieforth 1989 
[DIRS 104370]; Stuckless et al. 1991 [DIRS 101159]; Fridrich et al. 1994 [DIRS 100575]; 
Luckey et al. 1996 [DIRS 100465]; Campana and Byer 1996 [DIRS 126814]; Paces et al. 2002 
[DIRS 158817]) 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. 
Based on dD and d18O data for the Yucca Mountain region, Benson and Klieforth 
(1989 [DIRS 104370], 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 [DIRS 104370], pp. 48 and 49, Figure 11) 
reported that the d18O values of groundwater in the vicinity of Yucca Mountain were lower for 
water with apparent 14C ages between 18.5- and 9-ka (thousand years before present) and were 
higher 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 [DIRS 104370], p. 42) also argued that groundwater 14C ages 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-60 November 2004 
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 [DIRS 108871], Table 2, Figure 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 [DIRS 101159], 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 13C (d13C), a high 14C activity, and 
isotopically heavy dD. This groundwater is either mixed with a second source of 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 [DIRS 101159], Figure 4). Groundwater at Pahute Mesa from 
borehole UE-20 a#2 has these characteristics and it was suggested by Stuckless et al. 
(1991 [DIRS 101159], p. 1414) as a possible third source for the groundwater at Yucca 
Mountain. 
Fridrich et al. (1994 [DIRS 100575], pp. 153 to 159) 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 [DIRS 100465], 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 [DIRS 126814], 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 percent 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 [DIRS 126814], 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 [DIRS 126814], Figure 5) to be a mixture 
of groundwaters having different 14C activities, with a mean age of 10.9- to 16.0-ka and a median 
age of 6.3- to 6.5-ka (Campana and Byer 1996 [DIRS 126814], Table 7). Approximately 20 to 
25 percent 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 [DIRS 126814], p. 476). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-61 November 2004 
Water in the Amargosa Desert originated from groundwater flow from Fortymile Canyon and 
Wash area and Crater Flat. 
Based on 234U/238U activity ratios in perched water and the underlying groundwater, Paces et al. 
(2002 [DIRS 158817]) concluded that at least some of the shallow groundwater presently 
beneath Yucca Mountain appears to have been recharged locally. Paces et al. (2002 
[DIRS 158817], p. 770) suggested a conceptual model that explains the presence of 
high 234U/238U data in the saturated zone beneath Yucca Mountain. The hydraulic barriers that 
cause the comparatively large hydraulic gradients in the northern and western parts of Yucca 
Mountain inhibit underflow from upgradient areas, thereby allowing the chemical and isotopic 
composition of a small amount of local recharge to exert a prominent influence on the isotopic 
and chemical composition of the groundwater. Likewise, because both the present-day recharge 
rates and rates of groundwater flow from upgradient areas are small, hydraulic gradients beneath 
Yucca Mountain are relatively flat and groundwater that was recharged at Yucca Mountain in the 
late Pleistocene continues to persist in the groundwater beneath the Yucca Mountain (Paces et al. 
2002 [DIRS 158817], p. 770). The absence of high 234U/238U activity ratios in groundwater 
downgradient from Yucca Mountain could reflect the hydraulic isolation of Yucca Mountain, 
dilution by Fortymile Wash groundwater or other Yucca Mountain recharge with lower 234U/238U 
activity ratios (bulk-rock dissolution seems to have lowered 234U/238U activity ratios in perched 
water at borehole USW SD-7 (Paces et al. 2002 [DIRS 158817], p. 768)), water/rock interactions 
that incorporate other sources of uranium, or the upwelling of small amounts of groundwater 
from the carbonate aquifer. 
Winograd and Thordarson (1975 [DIRS 101167], p. C111) concluded from chemical data that 
groundwater in the central Amargosa Desert (Figure A6-1) 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 [DIRS 101167], 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 [DIRS 101167], 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 [DIRS 101125]) and White and Chuma (1987 [DIRS 108871]) presented 
different hypotheses regarding the origin of water in the northern Amargosa Desert near the 
present-day Fortymile Wash drainage. Claassen (1985 [DIRS 101125], 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 
[DIRS 101125], Figure 15), and on the high ratio of calcium plus magnesium to sodium plus 
potassium [(Ca + Mg)/(Na + K)] of groundwater from the northern Amargosa Desert compared 
to groundwater from upgradient locations (Claassen 1985 [DIRS 101125], p. F13, Figure 9). 
The 234U/238U activity ratios and dD values of groundwater near Fortymile Wash in the northern 
Amargosa Desert were also later interpreted as supportive of this hypothesis (Paces et al. 2002 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-62 November 2004 
[DIRS 158817], p. 767). In contrast, White and Chuma (1987 [DIRS 108871], 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 [DIRS 108871], p. 578). 
A6.3 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 eleven major subsections. Section A6.3.1 discusses factors 
affecting the chemical and isotopic composition of groundwater. In section A6.3.2 all 
groundwater samples evaluated in this appendix are assigned to a specific grouping to facilitate 
interpretation and discussion. Section A6.3.3 discusses depth-dependent trends in the chemical 
and isotopic composition of groundwater. Section A6.3.4 presents areal distribution maps of 
hydrochemical data and discusses geographic trends shown by these data. Section A6.3.5 
presents areal distribution maps showing calculated geochemical parameters such as mineral 
saturation indices. Section A6.3.6 presents an evaluation of the evidence regarding local 
recharge at Yucca Mountain. Also discussed in this subsection are evaluations of the evidence 
for the timing and magnitude of recharge. Section A6.3.7 presents an evaluation of mixing 
relations among groundwaters. Section A6.3.8 presents an analysis of mixing and water rock 
interactions using PHREEQC V2.3 (BSC 2001 [DIRS 155323]). Section A6.3.9 addresses 
groundwater flow velocities. Section A6.3.10 presents results of the site-scale saturated zone 
groundwater flow model for a portion of the study area. Section A6.3.11 presents an analysis of 
groundwater flow paths in the Yucca Mountain region based on cumulative evidence presented 
in the previous sections. 
The data derived from the DTNs and other sources are summarized here for each sample/well 
location for the major ions (Table A6-1) and for the isotopes and trace elements (Table A6-2). 
Where multiple sets of data were available for a location/sample, these data were averaged to 
derive the values shown in these two tables, and the areal distribution of the hydrochemical and 
isotopic data discussed in this section and portrayed on figures of the area of study uses the 
compiled values of Tables A6-1 and A6-2. All analytical data have uncertainty associated with 
the individual values, as fully described in Sections A7.3.1 and A7.3.2. Because these samples 
were collected over a time-span of several decades by different organizations using different 
methods, analytical precision and accuracy may be variable for particular analytes. In many 
cases, the original data sources do not provide an indication of the precision or accuracy. 
However, a sense of the uncertainties associated with historic measurements can be obtained 
from data that are more recently collected; uncertainties in historic data are probably higher than 
the values listed below because of recent developments in measurement technology. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-63 November 2004 
Analytical accuracy for recent measurements are (Section A7.3.1): 
 Ten percent for major anions, cations and strontium concentration, except for fluoride, 
for which accuracy is estimated as better than 15 percent. In some cases, strontium 
was determined by isotope dilution, mass spectrometry methods, for which data are 
more precise (e.g., 0.5 percent) 
 3.0 per mil for dD, 0.2 per mil for d18O, d13C, and d34S, and 0.1 pmc for 14C 
 Better than 1 percent for uranium concentrations and from 0.09 percent to 4.5 percent 
(with a mean of 0.73 percent) for 234U/238U 
 0.00001 for 87Sr/86Sr, which translates to an uncertainty of approximately 0.01 per mil 
in d87Sr units. 
An additional guide to the reliability of individual water analyses is also provided by the 
calculated charge-balance errors listed in Table A6-3. Groundwaters from most sites used in this 
analysis, especially those near Yucca Mountain itself, have charge-balance errors 
less than  5 percent. However, groundwaters from some outlying areas that were used as data 
in this analysis have charge-balance errors as high as 10-20 percent. These sample sites are 
located primarily in the Mine Mountain (MM) group of samples and did not have a significant 
influence on the conclusions derived in this analysis. 
MDL-NBS-HS-000011 REV 02 A-64 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
(C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Oasis Valley/NW Amargosa 
ER-EC-08 1 38.2 8.0 10.3 0.9 120.0 5.6 50.7 84.8 176.8 d 5.3 49.1 
ER-OV-01 2 25.7 8.3 6.2 0.1 139.7 6.8 45.6 82.7 196.9 1.7 2.1 70.0 
ER-OV-06a 3 28.6 8.3 2.1 0.7 144.5 7.5 48.5 80.0 197.9 3.0 3.1 52.9 
ER-OV-05 4 21.9 7.8 21.5 4.4 103.5 10.0 37.7 55.6 235.6  1.7 82.4 
ER-OV-02 5 18.9 8.2 14.3 0.6 143.0 4.1 51.2 88.1 227.1  2.3 57.4 
Springdale Upper Well (10S/47E- 
32adc) (11/12/97) 
6 23.6 7.7 22.0 4.1 130.0 8.7 37.2 67.7 292.8  2.1 69.9 
Goss Springs North (11S/47E-10bad) 
(11/13/97) 
7 17.7 8.2 16.4 1.2 107.0 5.0 43.0 76.4 180.1  2.4 53.2 
Er-OV-03a 8 17.5 8.1 14.0 1.0 118.0 5.2 42.6 76.0 183.6  2.3 54.7 
ER-OV-03a3 9 21.2 8.3 13.3 1.1 120.5 5.7 44.9 81.2 184.2  2.1 55.1 
ER-OV-03a2 10 20.0 9.2 5.7 1.0 331.0 84.7 262.0 295.0 186.2 41.6  20.0 
Goss Spring (11S/47E-10bcc) 11 22.0 7.7 17.5 1.3 116.5 5.1 45.0 78.1 181.0  2.8 50.4 
ER-OV-04a (11/07/97) 12 23.7 8.4 8.7 0.1 98.8 7.8 28.2 59.9 162.4 2.2 2.8 68.9 
Beatty Well no. 1 (Wat&Sanit Distr) 13 22.2 8.0 39.2 5.5 126.3 8.5 48.4 113.0 203.0  1.4  
Bond Gold Mining #1 14  8.3 23.0 6.0 65.0 7.3 40.0 52.0 161.0 0.0 0.6 29.0 
US Ecology MW-313 15  7.5 54.0 16.0 146.0 13.0 69.0 205.0 336.0 0.0 5.0 68.0 
US Ecology MW-600 16  7.9 20.0 11.5 167.5 8.8 67.5 153.0 296.0 0.0 5.2 62.5 
NECWell 17  7.6 54.9 14.1 170.1 10.2 79.1 190.2 328.3 0.0  70.3 
US Ecology MR-3 18  7.7       325.0 0.0   
Timber Mountain 
UE-18r 19 30.6 8.2 18.5 0.7 73.3 2.7 6.8 19.7 202.8 5.2 2.7 48.6 
ER-18-2 20 55.2 7.6 5.8 0.2 351.7 3.1 13.2 54.0 730.0  12.8 42.8 
ER-EC-05 21 29.9 8.0 20.3 0.6 73.9 1.7 16.2 35.5 176.8  4.7 40.9 
Coffer's Ranch Windmill Well 22 20.1 8.3 16.2 0.2 70.6 0.9 7.5 30.2 184.0  3.4 40.2 
ER-OV-03c 23 22.2 8.2 15.1 0.4 79.7 1.3 17.4 43.6 161.5  4.5 42.9 
ER-EC-07 24 30.0 7.9 21.6 1.7 36.8 3.1 6.0 18.3 148.8  1.5 44.0 
MDL-NBS-HS-000011 REV 02 A-65 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
(C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Fortymile WashNorth 
Water Well 8 25 24.2 7.3 7.9 1.2 31.1 3.3 7.3 15.0 78.0  0.7 50.0 
Test Well 1 (USGS HTH #1) 26 26.6 8.7 1.2 0.0 51.3 0.5 3.2 8.7 104.0   19.5 
UE-18t 27  8.6 22.2 1.0 141.0 8.2 64.4 10.8 331.0  7.0 
ER-30-1 (upper) 28 22.9 9.4 3.5 0.1 62.0 1.8 6.2 12.0 87.5 22.1 1.7 29.0 
ER-30-1 (lower) 29 24.3 9.2 2.1 0.1 65.0 1.0 6.5 9.9 106.3 11.1 1.4 25.0 
a#2(dp) 30 25.1 7.2 10.0 0.2 44.0 1.1 11.0 22.0 107.0 0.0 1.0 44.0 
a#2(sh) 31 22.7 7.0 10.0 0.3 44.0 1.3 8.8 21.0 107.0 0.0 0.9 44.0 
UE-29a#1 HTH 32 22.9 7.6 15.0 2.3 36.5 4.1 7.9 16.2 108.9 0.0 0.6 57.2 
WT#15 33 33.0b 7.5 12.0 1.7 62.0 4.6 12.0 16.0 166.0 0.0  52.0 
WT#14 34 30.0b 7.3 10.0 0.8 45.0 5.0 8.2 22.0 119.0 0.0  57.0 
J-13 35 31.0 7.2 12.0 2.1 42.0 5.0 7.1 17.0 124.0 0.0 2.4 57.0 
J-12 36 27.0 7.1 14.0 2.1 38.0 5.1 7.3 22.0 119.0 0.0 2.1 54.0 
JF#3 37 26.6 7.7 18.0 3.1 38.0 8.9 10.0 30.0 120.0 0.0 1.6 56.0 
Solitario Canyon Wash 
H-6(bh) 38 37.8 8.1 4.1 0.1 86.0 1.3 7.6 29.0 182.0 0.0 4.7 48.0 
H-6(Tct) 39 41.6 8.3 1.4 0.0 88.0 1.3 7.2 25.0 217.0 0.0 3.9 47.0 
H-6(Tcb) 40 37.2 8.3 4.7 0.1 88.0 1.4 7.4 32.0 234.0 0.0 4.7 49.0 
WT-7 41 34.0b 8.7 2.6 0.2 97.0 2.1 13.0 7.2 252.0 0.0  20.0 
WT-10 42 38.5 8.4 2.6 0.1 94.5 1.0 7.8 33.5 186.0 0.0 3.7 46.5 
Yucca MountainCrest 
G-2 43 34.2 7.5 7.7 0.5 46.0 5.3 6.5 15.0 121.0 0.0 1.0 51.0 
USW WT-24 44  7.9 0.3 0.036 59.0 1.6 6.7 15.0 119.0 0.0 0.9 53.0 
UZ-14(sh) 45 25.7 8.4 0.48 0.023 70.0 1.9 6.7 14.0 133 2.7 6.3 44 
UZ-14(dp) 46 27.5 8.4 0.2 0.030 74.0 1.9 7.7 14.0 137.0 3.0 6.7 47 
H-1(Tcp) 47 33.0 7.7 4.5 >01 51.0 2.4 5.7 18.0 115.0 0.0 1.2 47.0 
H-1(Tcb) 48 34.7 7.7 6.2 >0.1 51.0 1.6 5.8 19.0 122.0 0.0 1.0 40.0 
H-5 49 35.9 7.9 2.0 0.0 60.0 2.1 6.1 16.0 126.5 0.0 1.4 48.0 
MDL-NBS-HS-000011 REV 02 A-66 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Yucca MountainCrest Continued 
USW SD-6 50 35.0 8.4 0.4 0.0 90.6 1.5 6.8 26.7 181.8 2.5 4.7 45.6 
H-3 51 26.5 9.2 0.8 0.0 120.0 1.1 9.5 31.0 274.0 0.0 5.5 43.0 
Yucca MountainCentral 
G-4 52 35.6 7.7 13.0 0.2 57.0 2.1 5.9 19.0 139.0 0.0 2.5 45.0 
b#1(Tcb) 53 37.2 7.1 18.0 0.7 46.0 2.8 7.5 21.0 133.0 0.0 1.6 51.0 
b#1(bh) 54 36.0 7.3 18.0 0.7 49.5 3.6 10.8 23.0 156.0 0.0 1.6 52.5 
H-4 55 34.8 7.4 17.0 0.3 73.0 2.6 6.9 26.0 173.0 0.0 4.6 46.0 
UZ#16 56 30.0b  11.4 1.6 79.2  10.6 29.1 210.0 0.0  36.2 
Yucca MountainSoutheast 
ONC#1 57 31.0b 8.7 13.0 1.1 51.0 3.6 7.1 24.0 115.0 8.8  27.0 
c#1 58 41.5 7.6 11.0 0.3 56.0 2.0 7.4 23.0 151.0 0.0 2.1 56.0 
c#3 59 40.8 7.7 11.0 0.4 55.0 1.9 7.2 22.0 137.0 0.0 2.0 53.0 
c#3(95-97) 60 40.8c 7.7 11.0 0.3 57.0 1.9 6.5 19.0 141.0 0.0  58.0 
c#2 61 40.5 7.7 12.0 0.4 54.0 2.1 7.1 22.0 139.0 0.0 2.1 54.0 
p#1(v) 62 44.3 6.8 37.0 10.0 92.0 5.6 13.0 38.0 344.0 0.0 3.4 49.0 
p#1(c) 63 56.0 6.6 100.0 39.0 150.0 12.0 28.0 160.0 694.0 0.0 4.7 41.0 
WT-17 64 28.7 7.1 8.9 0.9 49.0 2.6 6.4 17.5 129.5 0.0 2.0 39.0 
WT#3 65 31.8 7.6 11.2 1.0 49.0 3.9 6.0 18.3 138.5 0.0 2.3 56.2 
WT#12 66 33.0b 7.6 15.0 0.3 66.0 2.6 7.8 28.0 167.0 0.0 3.1 47.0 
Jackass Flats 
UE-25 J-11 67  8.1 76.5 15.0 154.0 17.0 17.5 479.5 82.0 0.0 1.2 57.5 
Crater Flat 
GEXA Well4 68 31.8 7.9 11.5 0.4 71.0 3.3 13.5 45.5 150.0 0.0 3.2 48.0 
VH-1 69 35.4 7.6 10.3 1.5 79.0 1.9 10.3 44.3 164.7 0.0 2.7 49.7 
Southwest Crater Flat 
VH-2 70 32.8 7.1 78.5 29.8 70.8 8.1 16.0 142.5 391.8 0.0 1.1 26.3 
NC-EWDP-7S 71 21.5 7.3 77.0 37.0 86.0 8.2 19.5 167.0 420.0 0.0 1.0 23.0 
MDL-NBS-HS-000011 REV 02 A-67 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Southwest Crater Flat Continued 
NC-EWDP-7SC 72  7.2 83.0 38.0 90.7 4.3 22.0 179.0 429.0 0.0 0.9 23.7 
NC-EWDP-1DX 73  7.2 55.5 31.0 73.5 10.0 16.0 136.0 369.0 0.0 0.7 46.5 
NC-EWDP-1DX Zone 2 74 28.6 6.7 40.0 11.0 329.7 6.2 49.7 112.3 1011.5 0.0 11.0 51.3 
NC-EWDP-1S Zone 1 75 26.7 7.4 57.5 30.5 65.0 9.0 15.5 128.5 360.0 0.0 0.6 50.5 
NC-EWDP-1S Zone 2 76 27.6 7.3 55.5 30.5 64.5 8.9 15.5 126.0 356.0 0.0 0.6 48.5 
NC-EWDP-1S 77 27.8 7.3 59.0 31.0 67.5 8.6 15.0 127.0 358.0 0.0 0.6 55.0 
NC-EWDP-12PA 78 28.5 6.8 30.3 8.2 146.0 27.0 14.0 102.3 414.5 0.0 4.1 69.3 
NC-EWDP-12PB 79 29.3 6.9 30.5 8.2 140.5 27.0 14.0 105.0 396.5 0.0 4.2 68.0 
NC-EWDP-12PC 80 28.6 7.5 53.0 27.5 72.0 10.0 14.0 123.5 323.0 0.0 1.0 55.5 
Southern Yucca Mountain 
NC-EWDP-09SX 81 28.4 8.0 20.3 7.7 76 4.3 11.0 61.7 212.3 0.0 2.2 52.7 
NC-EWDP-9SX Zone 1 82 26.0 8.3 17.5 5.8 76.5 5.5 15.0 57.5 193.5 1.9 2.2 40.5 
NC-EWDP-9SX Zone 2 83 27.6 7.9 18.0 7.2 73.0 4.5 11.3 59.3 203.5 0.0 2.1 44.7 
NC-EWDP-9SX Zone 3 84 27.5 8.1 17.5 7.1 71.5 4.2 10.0 58.0 207.0 0.0 2.2 42.5 
NC-EWDP-9SX Zone 4 85 27.9 8.0 18.3 7.2 70.3 3.8 9.9 58.3 208.7 0.0 2.1 46.3 
NC-EWDP-03D 86 34.3 8.4 0.5 0.1 113.0 3.0 9.0 45.0 223.3 6.2 2.9 54.0 
NC-EWDP-3S Zone 2 87 32.2 8.7 0.8 0.1 127.5 1.8 18.0 47.5 224.5 11.7 3.0 59.0 
NC-EWDP-3S Zone 3 88 32.4 8.9 0.8 0.1 134.7 3.0 10.2 47.3 255.5 23.5 4.2 47.7 
CIND-R-LITE 89 50.0b 7.8 12.3 6.2 71.7 4.0 9.2 46.0 193.7 0.0 2.5 54.3 
NC-EWDP-15P 90 29.9 7.8 10.0 2.5 80.0 3.3 8.7 44.0 188.0 0.0 2.2 49.3 
NC-EWDP-02D 91  7.5 19.0 1.2 42.0 4.1 6.1 22.0 149.0 0.0 1.6 49.0 
NC-EWDP-19D 92 30.2 8.7 1.8 0.1 107.8 3.6 6.2 27.8 219.3 13.5 2.2 61.0 
NC-EWDP-19P 93 29.2 8.7 14.0 0.9 44.0 3.7 8.9 24.0 110.0 7.4 1.7 57.0 
NC-EWDP-19D (alluvial) 94 30.9 8.6 2.3 0.2 96.5 3.4 6.3 22.0 202.5 17.5 2.2 57.0 
NC-EWDP-19D (zone #1) 95 32.0 8.6 3.7 0.3 91.5 3.7 6.1 22.0 189.0 12.5 2.0 58.0 
NC-EWDP-19D (zone #2) 96 28.9 8.3 10.7 1.0 60.5 3.8 6.3 21.5 153.0 0.0 1.7 60.5 
NC-EWDP-19D (zone #3) 97 30.8 8.5 1.3 0.1 99.0 3.2 6.3 26.0 204.0 7.4 2.0 55.0 
MDL-NBS-HS-000011 REV 02 A-68 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Southern Yucca Mountain Continued 
NC-EWDP-19D (zone #4) 98 31.3 8.9 0.9 0.0 107.3 3.4 5.6 18.7 212.0 21.5 2.7 59.7 
Amargosa Valley 
NC-EWDP-4PB 99 24.2 9.5 6.7 0.0 67.0 1.9 5.5 34.7 63.0 40.7 1.7 32.0 
NC-EWDP-4PA 100 24.3 8.2 12.5 0.3 55.0 2.9 7.4 52.5 108.5 0.0 1.2 32.5 
Desert Farms Garlic Plot 101 26.2 7.8 30.0 2.1 71.0 5.1 13.0 117.0 125.0 0.0 0.8 40.0 
15S/49E-13dda 102             
15S/50E-18ccc 103  8.4 16.8 0.5 93.1 3.9 13.1 100 157 0.0 2.1 34.3 
NDOT 104 27.3 8.0 16.3 0.8 101.3 3.8 14.7 110.0 160.0 0.0 1.9 43.7 
15S/50E-18cdc 105 25.1 8.0 12.0 0.5 93.0 3.9 13.1 100.0 157.0 0.0 1.9 34.0 
Airport Well 106 27.6 8.7 5.6 0.1 69.0 1.5 6.6 45.0 116.0 6.2 1.8 38.0 
15S/50E-19b1 107 23.9 8.1 20.0 3.9 107.5 6.0 17.5 127.5 167.5 0.0 1.4 43.0 
Amargosa River 
16S/48E-8ba 108 25.0 7.9 58.5 6.3 180.5 12.9 79.8 202.7 295.9 0.0  37.9 
16S/48E-7bba 109 24.7 7.4 52.9 9.5 140.0 10.2 63.1 179.6 250.8 0.0  69.1 
16S/48E-7cbc 110 24.2 7.7 46.9 16.0 130.1 9.4 62.0 179.6 239.2 0.0  64.3 
16S/48E-18bcc 111  8.0 54.9 10.9 150.1 11.7 61.0 190.2 271.5 0.0  79.9 
16S/48E-17ccc 112  7.7 66.1 10.9 169.9 12.1 83.0 235.3 239.2 0.0  77.5 
16S/48E-18dad 113  7.7 52.9 8.5 149.9 10.6 63.1 187.3 236.1 0.0  76.9 
16S/48E-8cda 114 23.3 7.6 48.1 6.8 160.0 10.2 67.0 179.6 264.2 0.0  67.9 
16S/48E-17abb 115 24.0 7.4 60.1 7.8 157.0 12.1 69.1 178.7 302.0 0.0  75.1 
Barrachman Dom/Irr. 116 19.0 7.5 53.0 12.0 128.0 10.0 62.0 179.0 286.0 0.0 1.8 66.0 
McCracken Domestic 117 21.7 7.5 83.0 12.0 194.0 12.0 123.0 266.0 243.0 0.0 1.7 73.0 
Fortymile WashWest 
16S/48E-15ba 118 25.0 8.0 60.1 7.8 147.1 9.8 65.6 198.8 264.2 0.0  37.3 
16S/48E-10cba 119 24.5 8.3 9.2 3.9 60.9 5.5 8.2 32.7 166.0 0.0  64.3 
16S/48E-15aaa 120 25.5 8.1 9.6 3.2 57.9 5.9 7.4 27.9 153.2 0.0  67.9 
Selbach Domestic 121 23.9 8.0 23.0 8.1 90.0 6.6 36.0 96.0 178.0 0.0 1.4 68.0 
MDL-NBS-HS-000011 REV 02 A-69 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Fortymile WashWest Continued 
16S/48E-15dda 122  8.0 20.0 5.8 70.8 7.4 17.4 37.5 175.7 0.0  71.5 
16S/49E-23add 123  8.2 16.0 1.7 55.9 6.6 8.9 34.6 126.9 0.0  76.3 
16S/48E-23bdb 124 24.0 7.3 9.2 1.0 66.0 6.6 8.9 26.9 156.2 0.0  73.9 
16S/48E-23da 125 27.8 8.2 22.0 2.2 69.0 6.6 26.6 67.2 134.2 0.0   
Funeral Mountain Ranch Irrig. 126 22.2 8.2 12.0 2.4 80.0 7.0 12.0 43.0 200.0 0.0 2.3 87.0 
Fortymile WashSouth 
16S/49E-05acc 127  8.1 29.0 2.2 35.0 5.1 6.0 26.0 135.0 0.0 1.0 62.0 
16S/49E-8abb 128 23.0 7.5 30.1 2.7 37.0 5.5 7.8 29.8 151.9 0.0  54.1 
16S/49E-8acc 129 25.8 7.9 22.8 2.4 37.0 6.6 6.0 28.8 137.9 0.0  58.3 
16S/49E-18dc 130  8.1 20.0 2.7 42.1 9.0 7.4 27.9 150.1 0.0  58.9 
16s/48E-24aaa 131 27.0 8.1 18.0 0.7 54.0 7.0 7.8 29.8 147.1 0.0  78.7 
16S/49E-19daa 132 26.4 8.2 24.0 1.2 36.1 8.2 6.7 32.7 134.2 0.0  75.1 
DeLee Large Irrigation 133 14.6 8.0 24.0 1.1 37.0 8.4 6.2 25.0 135.0 0.0 1.1 76.5 
16S/48E-25aa 134 26.5 8.1 18.8 0.7 43.0 7.4 9.2 27.9 133.0 0.0  72.1 
16S/48E-36aaa 135  8.4 16.8 1.9 40.0 6.3 6.7 25.0 133.0 0.0  78.7 
Bray Domestic 136 20.9 8.0 22.0 1.8 35.0 8.8 7.9 25.0 131.0 0.0 1.0 74.0 
Amargosa Estates #2 137 24.0 8.1 20.0 2.1 38.0 6.8 6.5 22.0 134.0 0.0 1.6 79.0 
17S/48E-1ab 138  8.2 18.8 1.5 40.0 7.0 6.4 25.0 134.9 0.0  78.7 
17S/49E-7bb 139  8.3 24.0 1.7 48.0 7.4 9.6 30.7 153.2 0.0  79.9 
17S/49E-8ddb 140 24.0 8.4 20.8 2.7 36.1 7.4 6.4 26.9 123.3 0.0  80.8 
17S/49E-35ddd 141 23.0 8.0 15.2 4.6 50.6 8.2 6.7 40.3 157.4 0.0  81.1 
Fortymile WashEast 
15S/49E-22a1 142 27.8 8.0 25.0 2.4 41.0 5.2 8.0 33.0 145.0 0.0 1.4 52.0 
15S/49E-22dcc 143 29.5 6.7 27.0 2.0 43.0 4.6 8.5 33.0 149.0 0.0 1.0 49.0 
15S/49E-27acc 144 44.1 7.8 22.0 1.6 48.0 2.9 7.3 36.0 151.0 0.0 0.9 19.0 
O'Neill Domestic 145 19.5 7.9 26.0 2.4 44.0 7.6 7.4 43.0 141.0 0.0 0.8 65.0 
16S/49E-9cda 146 24.0 7.6 30.5 3.4 51.0 8.6 12.1 64.4 143.4 0.0  65.5 
MDL-NBS-HS-000011 REV 02 A-70 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Fortymile WashEast Continued 
16S/49E-9dcc 147 23.3 8.2 22.8 2.7 56.1 9.0 9.9 67.2 140.9 0.0  72.1 
16S/49E-16ccc 148  7.9 30.1 1.9 39.8 4.3 8.2 50.9 132.4 0.0  76.9 
Ponderosa Dairy #1 149 28.3 8.0 30.0 4.5 59.0 11.0 16.0 93.0 145.0 0.0 1.2 74.0 
17S/49E-9aa 150  8.0 24.8 3.6 48.0 9.8 9.9 69.2 131.2 0.0  70.3 
17S/49E-15bbd 151 22.5 8.1 20.8 3.9 31.3 8.2 9.9 34.6 120.2 0.0  72.7 
M. Gilgan Well 152 24.5 8.2 19.0 2.3 41.0 7.5 8.0 28.0 129.0 0.0 1.6 77.0 
17S/49E-15bc 153 24.0 8.2 21.6 1.0 39.1 6.6 10.6 27.9 122.0 0.0   
Gravity fault 
NC-EWDP-5S 154  8.3 17.0 3.5 149.0 11.0 39.0 146.0   1.0 3.7 
NC-EWDP-5SB 155 23.4 7.6 14.0 1.7 107.0 6.9 32.0 61.0 211.0 0.0 1.2 21.0 
16S/50E-7bcd 156 30.6 7.6 47.7 17.5 111.5 12.9 29.1 151.8 291.7 0.0  28.8 
Nelson Domestic 157 29.4 7.5 43.0 16.0 110.0 11.5 26.5 154.0 308.0 0.0 3.8 25.5 
16S/49E-12ddd 158  7.6 45.7 17.0 120.0 4.3 24.1 160.4 288.6 0.0  20.4 
Lowe Domestic 159 18.5 7.7 44.0 11.0 111.0 11.0 30.0 147.0 274.0 0.0 1.4 43.0 
16S/49E-15aaa 160 23.8 7.7 40.9 7.5 80.0 9.8 23.0 129.7 195.3 0.0  46.3 
Anvil Ranch Irrigation 161 20.5 7.9 47.0 5.8 68.0 13.0 40.0 120.0 138.0 0.0 1.1 71.0 
16S/49E-36aaa 162  7.8 52.1 22.1 120.0 18.0 26.9 168.1 314.3 0.0  37.9 
16S/49E-35baa 163 24.0 7.4 53.3 18.0 113.1 13.3 31.2 170.0 302.7 0.0  37.9 
Payton Domestic 164 20.2 7.6 51.0 19.0 107.0 16.0 41.0 155.0 290.0 0.0 3.9 36.0 
16S/49E-36aba 165  7.7 44.9 19.9 110.1 16.8 24.1 155.6 292.9 0.0  42.7 
16S/49E-35aaa 166  7.7 44.1 16.0 120.0 16.0 29.1 147.9 271.5 0.0  36.7 
Oettinger Well 167 25.2 7.5 50.0 16.0 103.0 15.0 29.0 157.0 291.0 0.0 3.3 39.0 
Amargosa Motel (b) 168 24.0 7.6 49.5 18.0 97.5 14.0 27.0 151.0 286.0 0.0 3.0 43.5 
17S/49E-11ba 169 22.0 8.1 40.1 14.1 97.0 14.1 28.0 160.4 209.9 0.0  52.9 
Spring Meadows Well #8 170 21.0  22.0 10.9 110.0 14.9 21.9 73.9 295.8  2.1 31.0 
17S/50E-19aab 171 16.0 8.6 7.6 8.5 252.0 27.4 69.8 175.8 415.5 0.0  42.7 
USFWS  Five Springs Well 172 33.5 7.5 47.0 20.0 67.5 7.9 23.3 82.0 304.0  1.6 21.8 
MDL-NBS-HS-000011 REV 02 A-71 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Gravity fault Continued 
Spring Meadows Well #10 173 19.5  2.8 2.9 250.0 14.9 25.8 105.1 494.0  3.2 67.0 
18S/49E-1aba 174 17.5 8.6 24.0 11.9 94.9 19.2 18.1 99.9 263.0 0.0  72.7 
18S/50E-6dac 175  8.2 23.6 11.9 102.5 13.7 20.6 106.6 230.0 0.0  80.5 
18S/50E-7aa 176 13.0 8.4 25.7 9.5 140.9 19.2 37.6 147.0 261.2 0.0  47.5 
Amargosa River/Fortymile Wash 
16S/48E-36dcc 177 26.0 7.2 54.9 9.7 100.0 12.9 33.0 110.5 300.2 0.0  70.3 
Crane Domestic 178 26.3 7.2 64.0 18.0 147.0 16.0 41.0 138.0 451.0 0.0 3.3 45.0 
27N/4E-27bbb 179 22.0 7.8 58.1 19.0 134.0 19.2 31.9 106.6 438.1 0.0  72.1 
IMV on Windjammer 180 23.5 7.5 45.0 9.9 100.0 11.0 30.5 89.0 303.0 0.0 2.8 67.5 
17S/49E-29acc 181 21.0 7.6 54.1 15.1 160.0 19.9 69.8 186.4 275.8 0.0  72.1 
17S/49E-28bcd 182  7.6 42.9 10.0 100.0 12.1 24.1 89.3 294.7 0.0  70.3 
18S/49E-2cbc 183 23.8 7.8 28.9 11.9 120.0 9.8 19.9 74.0 352.1 0.0  58.9 
Mom's Place 184 22.8 7.8 27.0 6.7 77.0 9.4 14.0 55.0 236.0 0.0 2.6 75.0 
18S/49E-11bbb 185 25.0 7.6 34.1 8.5 99.1 11.7 30.8 90.3 224.6 0.0  78.1 
Skeleton Hills 
TW-5 186 30.0 7.9 33.0 17.0 130.0 12.0 21.0 99.0 395.0 0.0 3.4 19.0 
Unnamed Well 15S/50E-22-7 187  6.7 27.0 2.0 43.0 4.6 8.5 33.0 148.8  0.9 49.0 
Amargosa Flat 
Amargosa Tracer Hole #2 188 30.5 8.0 42.8 18.5 63.8 7.5 21.0 68.7 279.2  1.9 22.0 
Cherry Patch Well, 17S/52E-08cdb 189 26.2 7.3 76.0 38.8 272.5 9.6 122.5 485.0 344.7  1.7 25.5 
USDOE-MSH-C shallow Well 190 20.5 8.0 16.0 17.0 81.0 9.4 17.0 58.0 261.0  1.7 34.0 
Mine Mountain 
UE-17a 191 27.0 7.6 41.0 29.9 80.0 3.0 27.7 95.5 200.0  0.9 11.8 
UE-1a 192 25.4 7.4 48.5 23.9 50.5 8.7 26.3  402.5  19.3 
UE-1b 193 27.4 7.4 37.4 13.7 31.3 10.7 5.9  184.0  80.9 
UE-16f 194 29.4 8.9 1.8 1.9 421.2 5.0 18.8 423.0 900.0 33.0 5.2 4.5 
UE-14b 195  8.4 10.5 0.2 77.5 1.5 7.1 80.8 116.0  43.8 
MDL-NBS-HS-000011 REV 02 A-72 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-1. Field Parameters and Major Ion Composition (Continued) 
Well Namea 
Figure 
A6-5 
Sample 
Temperature 
( C) pH 
Ca2+ 
(mg/L) 
Mg2+ 
(mg/L) 
Na+ 
(mg/L) 
K+ 
(mg/L) 
Cl 
(mg/L) 
SO4
2 
(mg/L) 
HCO3
 
(mg/L) 
CO3
2 
(mg/L) 
F 
(mg/L) 
SiO2 
(mg/L) 
Mine Mountain Continued 
Pluto 1 196  8.0 40.5 9.8 36.2 7.7 23.7 46.9 150.0   54.0 
Pluto 5 197  7.9 55.0 21.6 26.4 4.3 11.5 54.2 218.0   58.0 
USGS Test Well F (HTH) 198 64.5 6.9 46.0 16.7 63.0 9.1 12.9 79.3 254.2  3.2 36.4 
Funeral Mountains 
Woodcamp Spring 199 19.2 7.2 23.0 3.3 38.0 14.0 24.0 24.0 122.0  0.2 57.0 
Bond Gold Mining #13 200 32.4 7.3 144.5 79.5 85.5 7.0 63.5 621.5 274.5 0.0 0.6 16.5 
Nevares Spring 201 39.4 7.4 42.0 20.0 140.0 11.0 37.0 170.0 353.0  3.2 26.0 
Travertine Spring 202 35.3 7.4 33.0 18.0 140.0 12.0 37.0 150.0 343.0  3.7 30.0 
DTNs: LA0309RR831233.001 [DIRS 166546]; LA0309RR831233.002 [DIRS 166548]. 
a dp = 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 The groundwater temperature was estimated from the map of water table temperature shown in Fridrich et al. (1994 [DIRS 100575], Figure 8) 
c The groundwater temperature for this sample was assumed to be the same as for the c#3 sample. 
d The symbol  indicates the data are not available. 

MDL-NBS-HS-000011 REV 02 A-73 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g) 
234U/238U 
(AR) 
Sr2+ 
(g) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Oasis Valley/NW Amargosa 
ER-EC-08 1 -1.0 8.7 -116.0 -14.8  4.4   0.70864 -0.8 
ER-OV-01 2 -2.0 5.0 -112.5 -14.7  9.4 3.7 4.9 0.71058 1.9 
ER-OV-06a 3 -2.2 6.0 -113.0 -14.7  5.2 3.3 10.6 0.70932 0.2 
ER-OV-05 4 -3.1 17.3 -106.0 -13.7  2.2 2.8 192.0 0.70976 0.8 
ER-OV-02 5 -2.6 16.2 -112.0 -14.7  18.3 2.5 46.0 0.71006 1.2 
Springdale Upper Well (10S/47E-32adc) 6 -1.7 10.8 -104.0 -13.9  2.6 5.4 291.0 0.71026 1.5 
Goss Springs North (11S/47E-10bad) 7 -2.9 21.8 -110.0 -14.7  9.23 2.9 88.0 0.71039 1.7 
Er-OV-03a 8 -3.0 16.3 -111.0 -14.7  9.1 2.9 75.2 0.71029 1.5 
ER-OV-03a3 9 -2.8 16.5 -110.0 -14.6  9.1 2.9 76.8 0.71003 1.2 
ER-OV-03a2 10 -5.0 21.0 -109.0 -14.5  9.8 5.4 167.0 0.70809 -1.6 
Goss Spring (11S/47E-10bcc) 11  20.8 -111.7 -14.7  9.2 2.9 90.0 0.71050 1.8 
ER-OV-04a 12 -3.4 8.0 -109.5 -14.8  3.0 3.0 22.0 0.71006 1.2 
Beatty Well no. 1 (Wat & Sanit Distr) 13      8.8  155.3  
Bond Gold Mining #1 14 -8.8 12.8 -100.0 -13.8 15.7 0.1 3.5 150.0   
US Ecology MW-313 15 -6.1 17.0 -109.0 -14.1 21.8 7.8 3.2 361.0   
US Ecology MW-600 16 -8.4 19.3 -108.3 -14.4 19.5 4.9 2.5 340.0   
NECWell 17 -5.9 28.8         
US Ecology MR-3 18 -6.5 323.0 -109.0 -14.5 20.1 6.5 3.2    
Timber Mountain 
UE-18r 19 -1.7 7.7 -110.0 -14.7  5.1 6.1 116.5 0.70903 -0.2 
ER-18-2 20 -0.7 1.6 -112.0 -14.7  8.0 12.7 224.3 0.70872 -0.7 
ER-EC-05 21 -2.5 6.3 -113.0 -14.9  3.2 6.4 140.1 0.70916 -0.1 
Coffer's Ranch Windmill Well 22 -3.9 9.6 -103.9 -13.5  5.5 4.9 162.1 0.70922 0.0 
ER-OV-03c 23 -3.2 6.8 -109.0 -14.7  4.2 5.4 99.0 0.70924 0.1 
ER-EC-07 24 -6.3 36.5 -98.0 -13.2  1.8 7.2 123.1 0.70938 0.2 
Fortymile WashNorth 
Water Well 8 25 -11.6 25.0 -103.0 -13.5  0.4 3.9 5.2 0.71025 1.5 
MDL-NBS-HS-000011 REV 02 A-74 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Fortymile WashNorth Continued 
Test Well 1 (USGS HTH #1) 26 -10.2 30.1  -14.7  0.6  15.0 0.70892 -0.4 
UE-18t 27          
ER-30-1 (upper) 28 -6.3  -93.2 -12.4    13.0 0.70778 -2.0 
ER-30-1 (lower) 29 -6.0  -86.7 -11.8    7.0 0.70807 -1.59 
a#2(dp) 30 -12.6 62.3 -93.5 -12.8    39.0   
a#2(sh) 31 -13.1 60.0 -93.0 -12.8  0.7 4.0 33.0   
UE-29a#1 HTH 32 -10.5 75.7 -91.0 -12.6  1.5 3.6 54.7 0.71105 2.6 
WT#15 33 -11.8 21.6 -97.5 -13.2       
WT#14 34 -12.8 24.1 -97.5 -12.8       
J-13 35 -7.3 29.2 -97.5 -13.0  0.6 7.2 20.0 0.71146 3.2 
J-12 36 -7.9 32.2 -97.5 -12.8  0.3 5.5 10.0 0.71164 3.4 
JF#3 37 -8.6 30.7 -97.0 -13.2  0.8 4.1  0.71133 3.0 
Solitario Canyon Wash 
H-6(bh) 38 -7.5 16.3 -106.0 -13.8    8.0   
H-6(Tct) 39 -7.3 10.0 -105.0 -14.0    3.0   
H-6(Tcb) 40 -7.1 12.4 -107.0 -14.0    8.0   
WT-7 41 -9.0   -14.0  0.1 4.8  0.71027 1.5 
WT-10 42 -6.1 7.3 -103.0 -13.8  2.8 4.8 4.0 0.71007 1.2 
Yucca MountainCrest 
G-2 43 -11.8 20.5 -98.8 -13.3  1.2 7.6 10.0 0.71070 2.1 
USW WT-24 44 -10.6 27.3 -101.1 -13.2  1.1 6.4 1.5   
UZ-14(sh) 45 -14.1 24.6 -100.4 -14.0 11.4   57.0   
UZ-14(dp) 46 -14.4 21.1 -100.6 -14.0    32.0   
H-1(Tcp) 47  19.9 -103.0 -13.4    5.0   
H-1(Tcb) 48 -11.4 23.9 -101.0 -13.5    20.0   
H-5 49 -10.3 19.8 -102.0 -13.6    6.5   
MDL-NBS-HS-000011 REV 02 A-75 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Yucca MountainCrest Continued 
USW SD-6 50 -9.4  -105.3 -14.4 12.5 5.0 3.9 >1.0   
H-3 51 -4.9 10.5 -101.0 -13.9    1.0   
Yucca MountainCentral 
G-4 52 -9.1 22.0 -103.0 -13.8    17.0   
b#1(Tcb) 53 -8.6 18.9 -99.5 -13.5    47.0   
b#1(bh) 54 -10.6 16.7 -100.3 -13.4    41.0   
H-4 55 -7.4 11.8 -104.0 -14.0    27.0   
UZ#16 56           
Yucca MountainSoutheast 
ONC#1 57        1720.0 0.71040 1.7 
c#1 58 -7.1 15.0 -102.0 -13.5    30.0 0.71040 1.7 
c#3 59 -7.5 15.7 -103.0 -13.5    44.0   
c#3(95-97) 60   -99.7 -13.4 10.8 1.2 8.1 60.0 0.70981 0.9 
c#2 61 -7.0 16.6 -100.0 -13.4 10.9   45.0   
p#1(v) 62 -4.2 3.5 -106.0 -13.5    180.0   
p#1(c) 63 -2.3 2.3 -106.0 -13.8  13.3 2.3 450.0 0.71177 3.6 
WT-17 64 -8.3 16.2 -101.9 -13.7 10.5 1.1 7.6    
WT#3 65 -8.2 22.3 -102.1 -13.6 10.8 0.8 7.2 32.0   
WT#12 66 -8.1 11.4 -102.5 -13.8  2.5 7.2 23.0 0.70991 1.0 
Jackass Flats 
UE-25 J-11 67 -11.0 12.3 -105.3 -13.5 8.8 2.0 1.5 264.0   
Crater Flat 
GEXA Well4 68   -105.6 -14.1  3.0 5.1 34.0 0.70974 0.8 
VH-1 69 -8.5 12.2 -108.0 -14.2  3.6 5.5 66.7 0.71096 2.5 
Southwest Crater Flat 
VH-2 70   -99.5 -13.5  3.0 3.1 570.0 0.71300 5.4 
NC-EWDP-7S 71 -4.9 8.4 -98.0 -13.0 14.3   630.0   
MDL-NBS-HS-000011 REV 02 A-76 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Southwest Crater Flat Continued 
NC-EWDP-7SC 72        558.0   
NC-EWDP-1DX 73 -4.5  -101.3 -13.5 14.6 5.1 3.9 510.0   
NC-EWDP-1DX Zone 2 74 -2.1 2.5 -105.7 -14.7 28.3 0.0 3.0 981.0 0.71293 5.3 
NC-EWDP-1S Zone 1 75 -5.8 7.7 -101.3 -13.6 14.8 8.6 4.5 568.0 0.71279 5.1 
NC-EWDP-1S Zone 2 76 -5.6 7.2 -100.8 -13.7 15.2 7.6 4.5 533.0 0.71288 5.2 
NC-EWDP-1S 77 -5.6  -99.6 -13.8 14.5 8.6 4.5 557.0   
NC-EWDP-12PA 78 -3.4 4.7 -103.8 -13.6 16.9   302.0 0.71561 9.0 
NC-EWDP-12PB 79 -3.6 4.5 -100.5 -13.6 16.7   296.0 0.71460 7.6 
NC-EWDP-12PC 80 -5.3 9.0 -101.8 -13.4 14.7   462.0 0.71269 4.9 
Southern Yucca Mountain 
NC-EWDP-09SX 81 -6.5  -104.2 -14.0 13.3 5.1 5.0 151.3 0.71250 4.7 
NC-EWDP-9SX Zone 1 82 -7.1 12.2 -102.0 -14.3 14.2 4.6 4.9 129.0 0.71247 4.6 
NC-EWDP-9SX Zone 2 83 -7.0 11.4 -104.7 -14.3 13.9 4.6 5.0 149.0 0.71239 4.5 
NC-EWDP-9SX Zone 3 84 -6.8 10.9 -104.5 -14.1 14.4 4.4 5.0 144.5 0.71246 4.6 
NC-EWDP-9SX Zone 4 85 -6.2 11.0 -105.0 -14.2 13.8 4.6 5.0 146.7 0.71254 4.7 
NC-EWDP-03D 86 -6.8 10.0 -105.6 -14.4 11.2 2.0 3.4 1.3   
NC-EWDP-3S Zone 2 87 -8.4 21.5 -104.8 -14.3 10.9 2.6 3.2 2.5 0.71032 1.6 
NC-EWDP-3S Zone 3 88 -5.0 8.4 -106.2 -14.2 9.8 7.4 2.9 3.7 0.71100 2.5 
CIND-R-LITE 89   -102.0 -13.6  2.8 4.7 108.0 0.71221 4.2 
NC-EWDP-15P 90 -6.3 12.0 -106.3 -13.8 13.2   50.0 0.71222 4.3 
NC-EWDP-02D 91 -8.3 23.5 -104.0 -14.1 11.9 1.2 4.8 53.0   
NC-EWDP-19D 92 -7.6 12.4 -106.1 -13.8 9.0   3.5 0.71056 1.9 
NC-EWDP-19P 93 -9.5 23.5 -103.5 -13.6 11.7   57.0 0.71133 3.0 
NC-EWDP-19D (alluvial) 94 -7.1 12.4 -108.8 -13.8 10.7   7.5   
NC-EWDP-19D(zone #1) 95 -7.0 17.6 -109.0 -13.9 10.1   15.0   
NC-EWDP-19D(zone #2) 96 -7.6 21.0 -104.0 -13.6 10.6   36.0   
MDL-NBS-HS-000011 REV 02 A-77 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Southern Yucca Mountain Continued 
NC-EWDP-19D(zone #3) 97 -9.4 12.5 -106.3 -13.5 10.9   3.0   
NC-EWDP-19D(zone #4) 98 -6.4 11.2 -110.2 -13.9 11.7   2.0   
Amargosa Valley 
NC-EWDP-4PB 99 -10.0 15.9 -108.5 -13.9 9.6   36.0 0.71021 1.4 
NC-EWDP-4PA 100 -10.5 23.1 -101.3 -13.3 8.9   62.5 0.70949 0.4 
Desert Farms Garlic Plot 101 -9.1 8.8 -106.4 -13.1 8.8 1.3 3.4 144.0   
15S/49E-13dda 102           
15S/50E-18ccc 103        80.0   
NDOT 104      2.5 2.5  0.71081 2.3 
15S/50E-18cdc 105           
Airport Well 106 -10.3 10.5 -106.2 -13.2 8.7 0.6 3.1 24.0   
15S/50E-19b1 107           
Amargosa River 
16S/48E-8ba 108           
16S/48E-7bba 109           
16S/48E-7cbc 110 -6.2 31.4 -102.0 -13.1       
16S/48E-18bcc 111           
16S/48E-17ccc 112           
16S/48E-18dad 113 -5.7  -104.0 -13.6       
16S/48E-8cda 114           
16S/48E-17abb 115           
Barrachman Dom/Irr. 116 -5.8 17.9 -107.4 -13.5 20.9 5.2 3.4 473.0   
McCracken Domestic 117 -12.1 32.9 -102.7 -12.9 18.5 5.2 3.3 600.0 0.71456 7.6 
Fortymile WashWest 
16S/48E-15ba 118           
16S/48E-10cba 119 -5.6 15.6 -102.0 -13.4       
16S/48E-15aaa 120 -7.1 17.1 -103.0 -13.4       
MDL-NBS-HS-000011 REV 02 A-78 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Fortymile WashWest Continued 
Selbach Domestic 121 -8.1 30.7 -103.2 -12.9 10.9 2.7 4.2 217.0   
16S/48E-15dda 122           
16S/49E-23add 123 -8.4 27.4 -99.0 -13.2       
16S/48E-23bdb 124           
16S/48E-23da 125           
Funeral Mountain Ranch Irrig. 126 -5.5 6.5 -106.6 -13.7 13.2 1.3 2.9 114.0   
Fortymile WashSouth 
16S/49E-05acc 127 -7.1 19.3 -103.0 -13.2    50.0   
16S/49E-8abb 128 -6.8 21.4 -99.5 -13.2       
16S/49E-8acc 129           
16S/49E-18dc 130  28.4 -102.0 -12.6       
16s/48E-24aaa 131           
16S/49E-19daa 132  20.8 -101.0 -13.1       
DeLee Large Irrigation 133 -8.4 20.5 -104.1 -13.3 9.5 1.5 3.2 109.5   
16S/48E-25aa 134  19.3 -102.0 -13.0       
16S/48E-36aaa 135   -98.5 -12.6       
Bray Domestic 136 -10.0 23.5 -103.5 -13.2 9.3 1.5 3.1 101.0   
Amargosa Estates #2 137 -10.6 21.6 -104.3 -13.1 10.2 1.3 3.0 129.0   
17S/48E-1ab 138  18.4 -104.0 -13.0       
17S/49E-7bb 139  10.0 -104.0 -12.7       
17S/49E-8ddb 140  27.8 -102.0 -13.0       
17S/49E-35ddd 141  13.8 -102.0 -12.4       
Fortymile WashEast 
15S/49E-22a1 142           
15S/49E-22dcc 143        65.0   
15S/49E-27acc 144        65.0   
O'Neill Domestic 145 -6.7 17.7 -101.8 -13.2 9.6 1.7 2.8 109.0   
MDL-NBS-HS-000011 REV 02 A-79 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Fortymile WashEast Continued 
16S/49E-9cda 146           
16S/49E-9dcc 147 -7.3 21.9 -103.0 -13.4       
16S/49E-16ccc 148 -5.2 24.8 -97.5 -13.2       
Ponderosa Dairy #1 149 -7.2 14.2 -105.5 -13.3 16.6 2.3 2.9 248.0   
17S/49E-9aa 150  18.9 -105.0 -12.8       
17S/49E-15bbd 151  40.3         
M. Gilgan Well 152 -9.0 27.9 -100.1 -13.0 9.4 0.8 3.0 155.0   
17S/49E-15bc 153           
Gravity fault 
NC-EWDP-5S 154   -107.0 -14.0  0.04 6.7 361.0 0.71206 4.0 
NC-EWDP-5SB 155 -1.5 4.0 -107.0 -13.3 17.8   204.0 0.71232 4.4 
16S/50E-7bcd 156 -3.6 7.0 -105.0 -13.8       
Nelson Domestic 157 -2.0 0.9 -110.2 -13.8 22.6 1.7 3.2 829.5   
16S/49E-12ddd 158           
Lowe Domestic 159 -3.0 1.2 -103.7 -13.8 21.5 2.8 3.3 724.0   
16S/49E-15aaa 160 -3.4  -105.0 -13.8       
Anvil Ranch Irrigation 161 -10.4 11.8 -103.3 -13.1 13.2 2.1 2.8 319.0   
16S/49E-36aaa 162 -4.4 10.3 -104.0 -13.7       
16S/49E-35baa 163           
Payton Domestic 164 -2.7 3.3 -109.7 -13.8 21.7 1.0 3.6 1069.0   
16S/49E-36aba 165           
16S/49E-35aaa 166           
Oettinger Well 167 -2.6 1.4 -108.5 -13.8 21.8 1.5 3.3 915.0   
Amargosa Motel (b) 168 -3.0 1.9 -109.0 -13.7 22.0 1.6 3.2 954.0   
17S/49E-11ba 169           
Spring Meadows Well #8 170           
17S/50E-19aab 171           
MDL-NBS-HS-000011 REV 02 A-80 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Gravity fault Continued 
USFWS  Five Springs Well 172   -104.0 -13.6    860.0   
Spring Meadows Well #10 173           
18S/49E-1aba 174           
18S/50E-6dac 175           
18S/50E-7aa 176           
Amargosa River/Fortymile Wash 
16S/48E-36dcc 177           
Crane Domestic 178 -4.3 7.9 -108.8 -13.4 22.3 4.0 3.3 674.0   
27N/4E-27bbb 179           
IMV on Windjammer 180 -5.0 6.6 -104.0 -13.4 19.3 3.6 3.0 430.0   
17S/49E-29acc 181           
17S/49E-28bcd 182           
18S/49E-2cbc 183           
Mom's Place 184 -4.9 11.4 -105.5 -13.2 17.1 1.9 3.0 346.0   
18S/49E-11bbb 185           
Skeleton Hills 
TW-5 186   -113.2 -15.4    1509.0 0.71505 8.2 
Unnamed Well 15S/50E-22-7 187        80.0   
Amargosa Flat 
Amargosa Tracer Hole #2 188 -6.0 4.6  -13.6    790.0   
Cherry Patch Well, 17S/52E-08cdb 189      1.8 2.9 1500.0   
USDOE-MSH-C shallow Well 190   -108.0 -14.1    540.0   
Mine Mountain 
UE-17a 191 -9.9 4.9 -100.0 -13.3  0.4  829.0 0.71020 1.5 
UE-1a 192 -8.6 60.5 -103.0 -13.5  4.3  630.0 0.70957 0.5 
UE-1b 193 -4.5 16.0 -105.0   4.3  470.0 0.70950 0.4 
UE-16f 194 -11.7 3.4 -104.0 -13.5    550.0 0.71138 3.1 
MDL-NBS-HS-000011 REV 02 A-81 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-2. Isotope and Trace Element Composition (Continued) 
Well Name 
Figure 
A6-5 
Sample 
d13C 
(per mil) 
14C 
(pmc) 
dD 
(per mil) 
d18O 
(per mil) 
d34S 
(per mil) 
U 
(g /L) 
234U/238U 
(AR) 
Sr2+ 
(g /L) 
87Sr/86Sr 
(ratio) 
d87Sr 
(per mil) 
Mine Mountain Continued 
UE-14b 195           
Pluto 1 196           
Pluto 5 197           
USGS Test Well F (HTH) 198        570.0   
Funeral Mountains 
Woodcamp Spring 199 -12.2 78.0 -91.6 -12.4    20.0 0.70871 -0.7 
Bond Gold Mining #13 200 -7.5 8.1 -100.6 -13.3 29.3 8.1 1.9 2140.0 0.72732 25.5 
Nevares Spring 201 -5.5 3.0 -101.0 -13.5  1.3 2.1 1100.0 0.71679 10.7 
Travertine Spring 202 -3.8 3.3 -102.0 -13.5  3.3 2.4 1100.0 0.71734 11.5 
DTNs: LA0309RR831233.001[DIRS 166546]; LA0309RR831233.002 [DIRS 166548] 
AR = activity ratio 

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A6.3.1 Factors Affecting the Chemical and Isotopic Composition of Groundwater 
This section will summarize the study of Meijer (2002 [DIRS 158813]) that describes the effects 
of: (1) precipitation composition, (2) evaporation, (3) precipitation/dissolution reactions, 
(4) adsorption and ion-exchange reactions, and (5) climate change on the chemical composition 
of groundwater. Additional details are presented in Meijer (2002 [DIRS 158813]) and in the 
Yucca Mountain Site Description (BSC 2004 [DIRS 169734], Sections 5.2.2, 8.2.7 and 8.3.6). 
A6.3.1.1 Factors Affecting the Chemical Composition of Groundwater 
The main processes that control groundwater chemistry are: 
 Precipitation (atmospheric) quantities and compositions 
 Surface water quantities and compositions in recharge areas and along stream courses 
 Soil-zone processes in recharge areas and along flow paths between the soil and 
saturated zone 
 Rock-water interactions in the unsaturated zone 
 Rock-water interactions in the saturated zone 
 Temperature and pressure effects in the unsaturated and saturated zones 
 Mixing of groundwater from different flow systems. 
Although all the processes listed above may affect the groundwater chemistry, mixing and 
rock-water interactions generally are the most dominant in determining changes to the major-ion 
composition of recharge after it has reached the saturated zone. 
Processes that affect infiltrating waters in the soil zone or the unsaturated zone include 
evapotranspiration, mineral and gas dissolution reactions, gas ex-solution and 
mineral-precipitation reactions, and ion-exchange reactions. The dominant changes to the water 
compositions that result from these processes in the volcanic rock in the Yucca Mountain area 
are increases in the concentration of all chemical species and major relative increases in SiO2, 
Na+, and HCO3
 compared to the composition of precipitation. 
The dominant water-rock reactions that impact the water chemistry after the shallow 
unsaturated-zone or soil-zone reactions are SiO2-precipitation reactions and ion-exchange 
reactions involving minerals such as zeolites and clays. The cation-hydrogen ion-exchange 
reaction will also continue to be of significance. The ion-exchange reactions lead to increased 
Na+ concentrations and decreased Ca2+, Mg2+, and K+ concentrations in the waters. However, 
changes in the concentrations of these ions will only occur if zeolites and/or clays are present in 
adequate quantities in rock units through which the waters migrate. The Na+-H+ ion-exchange 
reaction will continue to increase the Na+ content of the waters until thermodynamic equilibrium 
is achieved with the host rock. 
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The primary controls on the pH of groundwater in the saturated zone are the partial pressure of 
CO2 and the rate at which hydrogen ions are consumed by the rock-mineral matrix. In the 
saturated zone, access to the CO2 reservoir in the gas phase of the unsaturated zone becomes 
progressively more difficult with depth. Therefore, unless a secondary source of H2CO3 or 
another source of acidity (e.g., sulfide minerals) exists in the saturated zone, the reaction of 
hydrogen ions with the rock mineral matrix will eventually consume the available acidity, 
leading to increased pH. 
Winograd and Thordarson (1975 [DIRS 101167], pp. C97 to C102, Plate C) identified 
six hydrochemical facies in the vicinity of the Nevada Test Site. Where the host rocks are 
limestone and dolomite, as in the case of the carbonate aquifer, the dominant ions are Ca2+, 
Mg2+, and HCO3
. Tuffaceous aquifers are characterized by groundwater having Na+, K+ and 
HCO3
 as the dominant ions. Groundwater of mixed compositions occurs where groundwater 
flows from one aquifer type into another, or from alluvium derived from one rock type into 
alluvium derived from another rock type. Groundwater mixing can also produce groundwaters 
that are intermediate in compositions between the carbonate and tuffaceous aquifers. In the 
alluvial valley fill deposits, the host rocks consist of fragments that reflect the rock composition 
in the upland sediment source areas. For example, in the west central Amargosa Desert, a central 
region of predominantly tuffaceous valley fill is flanked to the east and west by zones containing 
significant proportions of carbonate-rock detritus (Claassen 1985 [DIRS 101125], p. F5, 
Figure 1), which greatly affect the major-ion composition of the groundwater. This lateral 
sedimentary facies relationship is further complicated in the Amargosa Desert by the local 
presence of playa deposits (Claassen 1985 [DIRS 101125], pp. F5, F30). Groundwater in the 
vicinity of playa deposits typically contains greater concentrations of SO4
2 and Cl, which were 
concentrated in the playa deposits through earlier cycles of evaporation (Claassen 1985 
[DIRS 101125], p. F18). 
A6.3.1.2 Factors Affecting the Isotopic Composition of Groundwater 
The main processes that control the isotopic chemistry of SZ groundwaters have some common 
ground with those that control major-ion chemistry; however, major differences exist between 
these chemical regimes. As with major-ion content, precipitation quantity and composition are 
the starting point for the isotopic evolution of groundwater. 
A6.3.1.2.1 Hydrogen and Oxygen 
Hydrogen and oxygen isotope ratios are useful for tracing groundwater movement where spatial 
differences in their concentrations exist. 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. A6-1) 
The standard used for these measurements is known as Vienna Standard Mean Ocean Water 
(Clark and Fritz 1997 [DIRS 105738], p. 8). 
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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. A6-2) 
Vienna Standard Mean Ocean Water is also used as the standard for oxygen isotope 
measurements (Clark and Fritz 1997 [DIRS 105738], p. 8). 
The 2H and 18O atoms are part of the water molecule and, at low temperatures, are generally 
unaffected by water-rock interactions. 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 [DIRS 105738], Sections 2 to 4, 9). Some 
of the net effects of these processes are depicted in Figure A6-4. 
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 [DIRS 105738], p. 36). The slope of the line is related to the 
ratio of the equilibrium fractionation factors for 2H and 18O, which are approximately 8.2 at 25C 
(Clark and Fritz 1997 [DIRS 105738], 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 eight. This excess is inversely related to the relative humidity of 
the air in the moisture source area (Clark and Fritz 1997 [DIRS 105738], p. 45; Merlivat and 
Jouzel 1979 [DIRS 126847], 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 
14C 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 [DIRS 105738], pp. 198 to 199, Figure 8-2). 
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MDL-NBS-HS-000011 REV 02 A-85 November 2004 
Source: Based on Clark and Fritz (1997 [DIRS 105738], Figures 2-1, 2-9, 2-11, and 9-1). The possible 
paleometeoric water line for the Amargosa Desert area is based on arguments in White and Chuma, 1987 
[DIRS 108871], p. 573). 
Figure A6-4. 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 
volume-weighted 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 [DIRS 145088], 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 [DIRS 105738], Figure 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. Like evaporation, transpiration by plants increases the salinity of 
soil moisture; however, transpiration is a nonfractionating process and does not result in isotopic 
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MDL-NBS-HS-000011 REV 02 A-86 November 2004 
enrichment of the residual soil moisture (Clark and Fritz [DIRS 105738], pp. 80, 94). The 
relative importance of evaporation and transpiration on soil water loss can be evaluated by 
examining if increases in soil-water salinity are accompanied by corresponding increases in dD 
and d18O compositions along an evaporation trend. 
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 [DIRS 105738], pp. 250 to 255). 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 [DIRS 105738], Figure 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 interactions as oxygen isotope ratios because rocks 
generally contain much less hydrogen than water on a volume-to-volume basis. 
A6.3.1.2.2 Carbon 
Carbon has two stable isotopes 12C and 13C and a third isotope, 14C, which is radioactive. 
Carbon-14 is produced in the atmosphere by interactions of nitrogen and cosmic rays that 
bombard the earth constantly. The reaction can be described as 14N (n,p) . 14C. 14C is rapidly 
mixed in the atmosphere and incorporated into the CO2 molecule where it is then available for 
incorporation into terrestrial carbonaceous material. The radioactive decay of 14C, with a halflife 
(t1/2) of 5,730 years (Clark and Fritz 1997 [DIRS 105738], Table 1-3), forms the basis for 
radiocarbon dating. The 14C age of a sample is calculated by the following equation: 
t = (1/.) ln (14A/14A0) (Eq. A6-3) 
where 
t is the mean groundwater age (yr) 
. is the radioactive decay constant, equal to ln (2)/t1/2: 1.21 x 10-4 yr-1 
(Clark and Fritz 1997 [DIRS 105738], p. 201) 
14A is the measured 14C activity 
14A0 is the assumed initial activity. 
14C ages are typically expressed in percent modern carbon (pmc). A 14C activity of 100 pmc is 
taken as the 14C activity of the atmosphere in the year 1890, before the natural 14A of the 
atmosphere was diluted by large amounts of 14C-free carbon-dioxide gas from the burning of 
fossil fuel (Clark and Fritz 1997 [DIRS 105738], p. 18). 
Theoretically, the activity of 14C in a groundwater sample reflects the time at which the water 
was recharged. Unfortunately, precipitation is generally very dilute and has a high affinity for 
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MDL-NBS-HS-000011 REV 02 A-87 November 2004 
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 orders of magnitude 
(Langmuir 1997 [DIRS 100051], p. 292, Table 8.7; Meijer 2002 [DIRS 158813]). Because 
bicarbonate is the principal 14C-containing 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. A6-4) 
The standard used for reporting stable carbon isotope measurements is carbon from a belemnite 
fossil from the Cretaceous Pee Dee Formation belemnite in South Carolina (Clark and Fritz 1997 
[DIRS 105738], 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 [DIRS 109425], 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 
[DIRS 109425], Figure 16; Whelan et al. 1998 [DIRS 137305], Figure 5). Paleozoic carbonate 
rocks typically have d13C values close to 0 per mil (Forester et al. 1999 [DIRS 109425], 
Figure 16; Whelan et al. 1998 [DIRS 137305], Figure 5). 
A6.3.1.2.3 Sulfur 
Four stable isotopes of sulfur occur in nature; of these 32S and 34S are the most abundant. The 
sulfur isotopes are fractionated as a result of reduction of sulfate and by isotope exchange 
reactions. The isotopic composition of sulfur is expressed in terms of delta-34S (d34S) as defined 
by: 
d34S = [(34S/32S)sample/(34S/32S)standard  1] x 1000 (Eq. A6-5) 
The standard used for reporting d34S is the troilite (FeS) phase of the Canon Diablo meteorite 
(CDT), which has a 34S/32S ratio of 0.0450. Analytical precision is generally greater than 
0.3 per mil (Clark and Fritz 1997 [DIRS 105738], p. 11). 
In groundwater, sulfur is transported principally as the conservative ion SO4
2 and thus is a 
potentially useful indicator of groundwater mixing. Dissolution of solids containing sulfur can 
also readily change the d34S of groundwater. Of particular importance for this study is the fact 
the early Paleozoic marine carbonate that forms the carbonate aquifer near Yucca Mountain and, 
presumably, the groundwater from this aquifer, should both have distinctly high d34S values 
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MDL-NBS-HS-000011 REV 02 A-88 November 2004 
(25 to 30 per mil) compared to volcanic aquifer groundwater (Clark and Fritz 1997 
[DIRS 105738], pp. 138 to 148, Figures. 6-1 and 6-2). The d34S in volcanic environments is 
about 0 2 per mil where the sulfur is in a reduced oxidation state and ranges from about 3 to 
15 per mil in more oxidizing environments (Clark and Fritz 1997 [DIRS 105738], Figure 6-1). 
A6.3.1.2.4 Uranium 
Uranium-234 (t1/2 = 2.45 x 105 yr) (Cheng et al. 2000 [DIRS 153475], p. 17) is part of the 238U 
(t1/2 = 4.47 x 109 yr) radioactive decay series (Clark and Fritz 1997 [DIRS 105738], Table 1-3). 
The 234U/238U activity ratio in rocks is generally close to the secular equilibrium value 1. 
However, 234U is typically enriched relative to 238U in groundwater (Activity ratios > 1; Osmond 
and Cowart 1992 [DIRS 145190], Figure 9.1). The primary causes for this enrichment are: 
preferential dissolution of 234U from crystallographic defects caused by alpha decay; the 
tendency for 234U atoms to be converted to the more soluble uranyl ion due to the effects of 
radiation-induced ionization (Gascoyne 1992 [DIRS 127184], Section 2.5.1), and direct ejection 
of 234Th (which decays in about 24 days to 234U) into groundwater by alpha recoil. Uranium 
activity ratios may be lowered by release of uranium from rock and minerals with 234U/238U 
ratios near secular equilibrium through dissolution. Consequently, the 234U/238U activity ratios 
are the result of the competing effects of enrichment processes and dissolution of 
uranium-bearing material. Given the long half-life of 234U relative to groundwater ages in this 
region, changes in the 234U/238U activity ratio due to 234U decay are insignificant. Removal of 
uranium from solution by precipitation or sorption decrease U concentrations, but these 
processes do not affect the isotopic ratio. Therefore, the isotopic ratio should be relatively 
constant along a groundwater pathway unless additional U is added to the groundwater through 
mixing or by mineral or glass dissolution, or recoil-related processes. 
A6.3.1.2.5 Strontium 
Strontium is a trace constituent in groundwaters, with concentrations typically ranging from 
10 g/L to 1,000 g/L. Strontium has four naturally occurring isotopes, 84Sr, 86Sr, 87Sr and 88Sr, 
all of which are stable. The absolute abundances of 84Sr, 86Sr and 88Sr do not change. In 
contrast, the absolute abundance of 87Sr is continually increasing because this nuclide is 
produced from decay of 87Rb. Therefore, the 87Sr/86Sr ratios of rocks and minerals continually 
increase; the present day 87Sr/86Sr ratio depends on the relative abundances of Rb to Sr and on 
their age (Faure 1986 [DIRS 105559], Section 8). Strontium in groundwater is acquired from the 
materials through which the water passes. The 87Sr/86Sr ratios in groundwater will evolve toward 
the isotopic composition of the host material along its flow path as water-rock reaction 
progresses. Strontium isotope ratios can therefore provide a record of groundwater sources, flow 
pathways, and water-rock interaction. 
Strontium isotope ratios are commonly expressed using the delta notation relative to a standard 
value according to the equation: 
d87Sr= [(87Sr/86Sr)sample/(87Sr/86Sr)standard  1] x 1000 (Eq. A6-6) 
where the (87Sr/86Sr)standard value is modern seawater with a ratio of 0.7092. 
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Strontium in the oceans has a residence time of about 5,000,000 years, considerably longer than 
oceanic mixing times, which are on the order of 1,000/yr (Faure 1986 [DIRS 105559], 
Section 11). As a result, the 87Sr/86Sr ratio of strontium in the open oceans is consistent globally. 
This ratio, however, has changed throughout the Phanerozoic in response to the relative 
contributions of the different rock types that are exposed to chemical weathering. The variations 
of the 87Sr/86Sr ratios throughout the Phanerozoic have been determined by analyzing unaltered 
samples of marine carbonate (e.g., Burke et al. 1982 [DIRS 162906]). This work and subsequent 
refinements by a number of other studies have produced a detailed history of the variations in 
oceanic 87Sr/86Sr ratios throughout the Phanerozoic. Such information can be quite useful when 
interpreting 87Sr/86Sr ratios of groundwater that has interacted with marine carbonate rock. 
A6.3.2 Assignment and Description of Hydrochemical Groupings in the Vicinity of Yucca 
Mountain 
Hydrochemical and isotopic data from over 200 groundwater samples are presented in this 
appendix. The locations of wells cited in this section are shown in Figure A6-5, with insets to 
show greater detail. As these maps show, the data are unevenly distributed throughout the Yucca 
Mountain region, with clusters of wells in central and northern Yucca Mountain, farming areas 
of the Amargosa Desert, and along U.S. Highway 95. Elsewhere, data are relatively sparse, 
particularly to the west and east of Yucca Mountain in Crater Flat and Jackass Flats, 
respectively. An important data gap also exists at Yucca Mountain itself, between the cluster of 
wells in central and northern Yucca Mountain, and the line of wells along U.S. Highway 95. The 
potential impact of these gaps in data coverage is to make mixing trends among groundwaters 
separated by the gaps less obvious. 
To facilitate interpretation and discussion, these samples are assigned to 22 different groups. 
Each group is identified by a unique symbol and color, which are used in plots throughout. 
Samples are numbered sequentially within groups. Numbering within and between groups 
generally increases from north to south, with the exception of the last three groups, Mine 
Mountain, Amargosa Flat, and Funeral Mountains. All groupings are based largely on 
geographic distribution, or geographic affiliation. Hydrochemical similarities and/or trends were 
also considered in the group assignments. Accordingly, some groups show a relatively uniform 
hydrochemical composition, whereas others show a spread in hydrochemistry and were grouped 
to emphasize this transition. A brief geographic and hydrochemical description of each group 
follows. Hydrochemistry of all samples is shown on trilinear (Piper) and scatter plots 
(Figures A6-6 through A6-8), with the groups divided into three separate figures for clarity. 
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NOTES: The figure has color-coded data points and should not be read in a black and white version. The upper 
right panel corresponds to the area marked insert A; the lower panel corresponds to the area marked 
insert B. UTM=Universal Transverse Mercator. 
Figure A6-5. Locations of Boreholes in the Vicinity of Yucca Mountain and the Northern Amargosa 
Desert 
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The Oasis Valley/northwest Amargosa Desert group (OV/NWA) comprises boreholes located 
from the northern part of Oasis Valley extending southward along the course of the Amargosa 
River to the west and south of Bare Mountain. Boreholes drilled as part of the Nye County Early 
Warning Drilling Program (NC-EWDP) are located along the southern edge of Crater Flat and 
extend southeasterly into Fortymile Wash. Most of these wells have been assigned into two 
groupings, Crater Flatsouthwest (CF-SW) and Yucca Mountain-south (YM-S), on the basis of 
geographic position and hydrochemistry. Two boreholes with similar chemistry comprise the 
Crater Flat group (CF). Boreholes to the north of Yucca Mountain are assigned to the Timber 
Mountain group (TM). A single borehole, though one with unique hydrochemical characteristics 
comprises the Jackass Flats group. Several tightly grouped boreholes along U.S. Highway 95 are 
assigned to the Amargosa Valley (formerly Lathrop Wells) group (LW). Finally, the boreholes 
in the northeast part of the study area are assigned to the Mine Mountain group. 
Most groundwaters from these regions are a sodium-bicarbonate type (Figure A6-6). Notable 
exceptions are those samples from the SW Crater Flat Group and the Mine Mountain Group, 
which contain greater Ca2+ + Mg2+ relative to Na+ + K+. These groundwaters either originate 
from the regional carbonate aquifer or have contacted alluvium derived from carbonate rocks and 
their greater Ca2+ + Mg2+ contents reflect the composition of these rock. The hydrochemical 
characteristics of groundwater beneath the broad area of Jackass Flats are represented by data 
from a single borehole (J-11), which has a unique chemical signature that may or may not be 
representative of regional groundwater flow in this area. 
Boreholes at Yucca Mountain were divided into (1) a western group designated Solitario Canyon 
Wash (SCW), which includes samples from west of the Solitario Canyon fault, (2) a group of 
samples that encompasses the crest of Yucca Mountain (Yucca Mountain-Crest YM-CR), (3) a 
central group (Yucca Mountain Central, YM-C), which includes boreholes located within the 
central block of Yucca Mountain, and (4) a southeastern group (Yucca Mountain-Southeast, 
YM-SE), which includes boreholes along and south of Dune Wash. Boreholes near Fortymile 
Wash east and northeast of Yucca Mountain are assigned to a northern Fortymile Wash North 
group (FMW-N), distinguishing them from samples along the course of the Fortymile Wash in 
the Amargosa Desert (discussed below). 
These groundwater are mostly sodium-bicarbonate water, typically with low total dissolved 
solids (TDS) (Figure A6-7). An important exception to this is the borehole p#1(c) sample from 
the YM-SE group (site 63), which penetrates to the carbonate aquifer. This sample is distinct 
from those from the volcanic aquifer in that it has higher calcium, magnesium, and TDS. The 
contribution of carbonate water in sample p#1(v) from the volcanic aquifer (site 62) is also 
evident in Figure A6-7. It was estimated that about 28.6 percent of the groundwater in this 
sample originated from upward flow in the borehole from the carbonate aquifer (Craig and 
Robison 1984 [DIRS 101040], p. 49). 
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Source: Table A6-1. 
NOTE: Units for the trilinear plots are percent milliequivalents per liter. Legend explained in text. 
Figure A6-6. Trilinear and Scatter Plots for Samples that Surround Yucca Mountain But Are Generally 
North of the Amargosa Valley 
Figure A6-8 shows hydrochemical characteristics from boreholes located south of 
U.S. Highway 95. The Amargosa River (AR) and Gravity fault (GF) groupings constitute 
boreholes located on the west and east sides of the Amargosa Desert, respectively. Groundwater 
from these groupings is typically sodium-calcium-bicarbonate-sulfate water type with higher 
TDS than samples in the central Amargosa Desert. Boreholes located along and near the main 
channel of Fortymile Wash in the Amargosa Desert are assigned to the Fortymile Wash-south 
(FMW-S) grouping. These are relatively dilute sodium-bicarbonate waters. The Amargosa 
River, Gravity fault and FMW-S groups, in general, represent three end-members of the 
hydrochemistry displayed in the Amargosa Desert region. Boreholes of the 
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MDL-NBS-HS-000011 REV 02 A-93 November 2004 
Fortymile Wash-East (FMW-E), Fortymile Wash-West (FMW-W) and Amargosa 
River/Fortymile Wash (AR/FMW) groupings are transitional between these end members. 
Boreholes near the Skeleton Hills and Specter Range Thrust fault are grouped together as 
Skeleton Hills (SH). Boreholes in the far east of the study area are assigned to the Amargosa 
Flat group (AF), and finally, the widely spaced samples along the western part of the study area 
are grouped as the Funeral Mountains (FMt) group. 
Source: Table A6-1. 
NOTE: Units for the trilinear plots are percent milliequivalents per liter. Legend explained in text. 
Figure A6-7. Trilinear and Scatter Plots for Samples from the Yucca Mountain Area 
Saturated Zone Site-Scale Flow Model 
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Source: Table A6-1. 
NOTE: Units for the trilinear plots are percent milliequivalents per liter. Legend explained in text. 
Figure A6-8. Trilinear and Scatter Plots for Samples from Groupings in the Amargosa Desert Region 
A6.3.3 Depth-Dependent Trends in the Chemical and Isotopic Composition of 
Groundwater 
This section describes groundwater samples from different depth intervals in single well or 
closely spaced wells to evaluate the relationship between hydrochemistry and depth and/or 
aquifer rock type. For most wells in the Yucca Mountain area, groundwater samples were 
obtained by pumping from an open borehole. In some boreholes, flow logs made during 
pumping indicate that much of the groundwater came from a relatively narrow depth interval, 
whereas in other boreholes, flow logs indicate the mixing of groundwater from different depth 
intervals. Sampling groundwater from an open borehole produces a groundwater composition 
that is naturally weighted by the permeability of the producing zones and which may be 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-95 November 2004 
representative of the average composition of groundwater flowing past the open interval of the 
borehole (see Section A6.3.4). However, it may also result in artificial mixing of groundwaters 
that would not otherwise mix and thereby obscure compositional differences that reflect different 
groundwater sources and rates of groundwater movement. This section examines data from the 
NC-EWDP wells obtained from discrete-interval sampling or from closely spaced wells and 
piezometers completed at different depths to assess the magnitude and importance of these 
differences. 
A6.3.3.1 Boreholes NC-EWDP-19D and -19P 
Groundwater samples were collected at borehole NC-EWDP-19D (Site 92) from the open 
borehole (composite sample), from the saturated alluvial section (Site 94), from zones 1 to 4 at 
different depth intervals within the alluvium (Sites 9598), and from the alluvium at nearby 
piezometer NC-EWDP-19P (Site 93). The screened interval in NC-EWDP-19P (109.5 to 
139.8-m depth) is slightly higher but overlaps with Zone 1 of NC-EWDP-19D (125.9 131.4 m). 
The open borehole sample from NC-EWDP-19D included contributions from a lithic ash flow 
tuff between depths of 251 and 379 m, whereas the remainder of the groundwater samples 
originated from the alluvium overlying the tuffs (DTN: LA0311EK831223.001 
[DIRS 165985]). The composition of groundwater from the open-hole and the composite 
alluvial interval likely reflect the relative amounts of inflow from different zones into the 
borehole during pumping. 
All of the groundwater samples from NC-EWDP-19D and -19P are characterized by low 
Cl-concentrations compared to Crater Flat area groundwater and very light d18O compared to 
northern Fortymile Wash area (FMW-N) groundwater found at boreholes J-13, J-12, and JF-3 
(Tables A6-1 and A6-2). Samples from wells NC-EWDP-19P and -19D (Zone 2) have higher 
concentrations of Ca2+ and Sr2+ (not shown, see Table A6-2), lower concentrations of Na+ and 
HCO3
-, heavier dD, and higher 14C activity compared to other alluvial groundwater from well 
NC-EWDP-19D (Figure A6-9). These compositional characteristics are compatible with less 
water-rock interaction and short residence times of groundwater in this interval compared with 
other intervals in the alluvium. However, hydraulic testing (BSC 2004 [DIRS 170010]) at 
NC-EWDP-19D indicated that Zone 4 was the most permeable zone in the immediate vicinity of 
the borehole. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-96 November 2004 
Source: Tables A6-1 and A6-2. 
NOTE: For plotting purposes only, Mg2+ concentration has been multiplied by 10, and the values for Na+, .D, and 
HCO3 have been divided by 10. 
Figure A6-9. Plots of Selected Hydrochemical Constituents for the Different Depth Intervals of Boreholes 
NC-EWDP-19D and -19P 
A6.3.3.2 Borehole NC-EWDP-9SX 
Groundwater from four depth intervals in borehole NC-EWDP-9SX (Sites 82 to 85) originates 
from the upper 91 m of the SZ just south of Crater Flat. The groundwater over this relatively 
narrow depth range is similar in all four-depth intervals (Figure A6-10). In general, 14C, d13C, 
dD, Na+, K+, and Cl decrease slightly and HCO3
- increases with depth in the borehole, but 
overall, there is relatively little chemical or isotopic variability within the depth range spanned 
by sampling Zones 1 to 4. In addition to the data shown in Figure A6-10, the Sr2+ concentration 
in Zone 1 is slightly less than in the other zones, but the d87Sr, d34S, and 234U/238U activity ratio 
data are very similar in all four zones (Table A6-2). The composite sample from borehole 
NC-EWDP-9SX (Site 81) has a composition that is similar to that of the individual zones but 
with slightly higher concentrations of Ca2+, Mg2+, Na+, SO4
2, SiO2, and Sr2+. The remainder of 
the chemical and isotopic species of the composite sample is similar or intermediate to those of 
the four individual zones. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-97 November 2004 
Source: Tables A6-1 and A6-2. 
NOTE: For plotting purposes only, the values for Na+, .D, and HCO3 have been divided by 10. 
Figure A6-10. Plots of Selected Hydrochemical Constituents for the Different Depth Intervals of Borehole 
NC-EWDP-9SX 
A6.3.3.3 Boreholes NC-EWDP-1DX and -1S 
Groundwater from shallow intervals (48.854.9 and 64.082.3 m) in borehole NC-EWDP-1S 
(Sites 75 to 76) shows large differences in both chemical and isotopic composition compared to 
deep groundwater (658.4 to 682.8 m) from Zone 2 (Site 74) in borehole NC-EWDP-1DX 
(Figure A6-11). Chemically, groundwater from Zone 2 in NC-EWDP-1DX has much higher 
Na+, Sr2+ (not shown, see Table A6-2), Cl, F (not shown, see Table A6-2), and HCO3
 
concentrations and has lower pH and lower Ca2+ and SO4
2 concentrations than the shallower 
groundwater from NC-EWDP-1S. The deep groundwater from Zone 2 of borehole NC-EWDP- 
1DX is heavier in d13C and d34S (not shown, see Table A6-2), lighter in d18O and dD, and has a 
lower 234U/238U activity ratio (not shown, see Table A6-2) than the shallow zones in NC-EWDP- 
1S (Figure A6-11 and Table A6-2). The composite groundwater samples from boreholes NCEWDP-
1S (Site 77) and NC-EWDP-1DX (Site 73) have similar isotopic and chemical 
compositions to the shallow groundwater samples from NC-EWDP-1S. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-98 November 2004 
Source: Tables A6-1 and A6-2. 
NOTE: For plotting purposes only, the values for Na+, .D, and HCO3 have been divided by 10. 
Figure A6-11. Plots of Selected Hydrochemical Constituents for the Different Depth Intervals of 
Boreholes NC-EWDP-1S and -1DX 
A6.3.3.4 Boreholes NC-EWDP-3D and -3S 
Groundwater at NC-EWDP-3S was sampled from Zone 2 between depths of 103.6 and 128.0 m 
(site 87) and from Zone 3 between depths of 146.3 and 160.0 m (Site 88) 
(DTN: GS010308312322.003 [DIRS 154734]). Well NC-EWDP-3D (Site 86) was drilled to 
762 m but was open between 159 to 292 m (DTN: LA0311EK831223.001 [DIRS 165985]). 
The groundwaters from these three sample locations have similar concentrations in most major 
ions with the exception that the sample from Zone 2 of NC-EWDP-3S is higher in Cl 
concentration, has higher 14C, and is lighter in d13C compared to the other two samples 
(Figure A6-12). Compared to other wells in the YM-S group, groundwater samples from 
NC-EWDP-3D and -3S are very low in divalent cations, including Ca2+, Mg2+, and Sr2+ (not 
shown, see Table A6-2). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-99 November 2004 
Source: Tables A6-1 and A6-2. 
NOTE: For plotting purposes only, Mg2+ concentration has been multiplied by 10, and the values for Na+, .D, and 
HCO3 have been divided by 10. 
Figure A6-12. Plots of Selected Hydrochemical Constituents for the Different Depth Intervals of 
Boreholes NC-EWDP-3S and NC-EWDP-3D 
A6.3.3.5 Boreholes NC-EWDP-12PA, -12PB, and -12PC 
Boreholes NC-EWDP-12PA (Site 78), -12PB (Site 79), and -12PC (Site 80) form a piezometer 
nest in the northern Amargosa Desert just south of western Crater Flat. As shown in Table A4-3, 
the open intervals of the piezometers in boreholes NC-EWDP-12PA and NC-EWDP-12PB are 
located about 46 m below the open interval in NC-EWDP-12PC. Groundwater from boreholes 
NC-EWDP-12PA and NC-EWDP-12PB is very similar with respect to almost all chemical 
species and isotopes (Figure A6-13). The shallower groundwater from NC-EWDP-12PC is 
higher in 14C, Ca2+, Mg2+, and SO4
2
, lower in K+, Na+, HCO3
, F (not shown, see Table A6-2), 
and SiO2, and lighter in d13C than groundwater from the other boreholes. The lower 14C and 
heavier d13C of the groundwater in boreholes NC-EWDP-12PA and -12PB indicates the deep 
groundwater has interacted with more carbonate rocks. The geologic map of the NTS and 
vicinity shows that a slide block of carbonate sedimentary rock from Bare Mountain outcrops 
along the low ridge bordering southern Crater Flat just north of these boreholes (Slate et al. 2000 
[DIRS 150228], Plate 1, p. 13). The groundwater at all three boreholes has similar d18O and dD 
to groundwater at borehole VH-2 in western Crater Flat (Table A6-2). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-100 November 2004 
Source: Tables A6-1 and A6-2. 
NOTE: For plotting purposes only, the values for Na+, .D, and HCO3 have been divided by 10. 
Figure A6-13. Plots of Selected Hydrochemical Constituents for the Different Depth Intervals of 
Boreholes NC-EWDP-12PA, -12PB and NC-EWDP-12PC 
A6.3.3.6 Summary of Depth-Dependent Trends in Groundwater Compositions 
Groundwater geochemical and isotopic data from five groups of NC-EWDP wells and 
piezometers along U.S. Highway 95 were examined to determine the extent of compositional 
changes with sampling depth. The changes with depth for most constituents were small at wells 
NC-EWDP-9SX, piezometers NC-EWDP-12PA, NC-EWDP-12PB and NC-EWDP-12PC, and 
wells NC-EWDP-3D and NC-EWDP-3S. This may be due, in part, to the relatively small range 
of depths sampled within each of these groups. For these groups, the composition of the 
groundwater sampled from the open borehole within the group does not substantially differ from 
any of the samples taken from a narrower depth interval. For wells NC-EWD-1DX and 
NC-EWD-1S, the deep (658.4682.8 m) sample from Zone 2 of NC-EWDP-1DX (Site 74) is 
very different from the other samples in this group. However, groundwater from Zone 2 does 
not appear to contribute significantly to the composition of groundwater pumped from the open 
interval of NC-EWDP-1DX (Site 73), which more closely resembles shallow groundwater from 
nearby well NC-EWDP-1S. This observation indicates that the deep groundwater from Zone 2 
at NC-EWDP-1DX may be relatively stagnant and not representative of the flowing groundwater 
composition at this location. Groundwaters from wells NC-EWDP-19D and NC-EWDP-19P 
have significant compositional variations with depth that indicate possible differences in 
groundwater sources, flow rates, or extent of water/rock interactions. The shallow groundwater 
from piezometer NC-EWDP-19P (Site 93) represents the composition of the shallowest and, 
perhaps, youngest groundwater in this area. The composite alluvial sample from well 
NC-EWDP-19D (Site 94) approximates the average composition of alluvial groundwater in this 
area. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-101 November 2004 
A6.3.4 Areal Distributions of Chemical and Isotopic Species 
In this section, 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 presented in this 
section are intended to be somewhat general in character. More detailed discussions are 
presented below. Many boreholes, particularly the Nye County-EWDP boreholes along U.S. 
Highway 95 (Yucca Mountain-South grouping) have numerous sampled intervals as discussed 
previously. In these cases, one value, which is considered to best represent the average value for 
that borehole and to best represent regional hydrochemical trends is plotted. Typically, data for 
groundwater samples pumped from the entire open interval of borehole are plotted in figures in 
Sections A6.3.4 and A6.3.5. Thus, the sampled groundwater compositions are naturally 
weighted toward the compositions in the most permeable intervals of the well, and the 
compositions of groundwater from less permeable zones attain less emphasis. These composite 
samples thus provide a good indication of the flux-weighted composition of groundwater 
actually moving past the well in the aquifer. (Note: One exception to this generalization exists in 
the case of NC-EWDP-19D, where the composite alluvial sample, rather than the composite 
borehole sample, was used.) Nonetheless, vertical heterogeneity displayed among the samples is 
recognized as an important element in evaluating the flow system. Although groundwater 
pumped from the open interval of a borehole may be representative of the average flowing 
composition, more detailed depth sampling, like that available for well NC-EWDP-19D 
(Section A6.3.3.1), does suggest that in some locations groundwaters may originate from 
different sources, travel at different velocities, or undergo different degrees of water/rock 
interaction. These groundwaters can become artificially mixed in samples pumped from large 
open intervals, partially obscuring details of the flow system. 
A6.3.4.1 pH 
Groundwater pH at Yucca Mountain varies between about 7 and 9 (Figure A6-14). Some of the 
higher pH values are found in the vicinity of Yucca Crest, with similarly high pH values found in 
groundwater associated with Solitario Canyon Wash. Groundwater in the carbonate aquifer at 
borehole p#1 (Site 63) has a distinctly lower pH value (6.6) compared to groundwater in the 
volcanic aquifer at Yucca Mountain. Groundwater to the north and northeast of Yucca Mountain 
also has a pH range of 7 to 9, with the highest values present in the northernmost part of 
Fortymile Wash. South of the northern boundary of the site model, groundwater pH along 
Fortymile Wash shows an overall increase from values of about 7.2 to 7.6 directly east of Yucca 
Mountain to values greater than 8 near Fortymile Wash in the Amargosa Desert. Groundwater 
pH values less than 8 generally are typical of the groundwater associated with the Amargosa 
River and Gravity fault areas (Figure A6-14). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-102 November 2004 
Source: Table A6-1. 
NOTES: This figure has color-coded data points and should not be read in a black and white version. 
The pH is log[H+] where [H+] is the activity of hydrogen ion in moles/L. UTM-X =UTM-Easting and 
UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-14. Areal Distribution of pH in Groundwater 
A6.3.4.2 Chloride 
The chloride (Cl) concentrations of groundwater samples in the Yucca Mountain vicinity are 
shown in Figure A6-15. The areal distribution clearly shows coherent spatial patterns in 
Cl-concentrations. Except for borehole p#1, where groundwater was sampled from the carbonate 
aquifer (Site 62) and from deep in the volcanic section (Site 62) 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/L) compared to areas to the west and 
east. Several wells to the north of Yucca Mountain in the Timber Mountain area have similarly 
low Cl concentrations. Groundwater from the Oasis Valley to the northwest of the site model 
area generally has Cl concentrations of 20 to 50 mg/L. These concentrations are slightly lower 
than the Cl concentrations of 50 mg/L or more measured in groundwater near the Nuclear 
Engineering Company (NEC) wells west of Bare Mountain or in groundwater in the southwest 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-103 November 2004 
corner of the site model boundary. Groundwater to the northeast and east of the site model 
boundary shows considerable variability between closely spaced wells, so that it is difficult to 
make generalizations about Cl concentrations in these areas. 
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. One borehole at the southern end of Crater Flat (Site 71  NC-EWDP-7S) 
has a relatively high Cl concentration of 18 to 20 mg/L. The depth to groundwater at this 
borehole is only about 7 m and groundwater in this area, like the shallow groundwater in Oasis 
Valley, may have been affected by evapotranspiration. Low Cl concentrations associated with 
the Fortymile Wash area east of Yucca Mountain extend southward into the Amargosa Desert, 
where the low-concentration zone is bounded by areas having substantially higher 
Cl- concentrations. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-15. Areal Distribution of Chloride in Groundwater 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-104 November 2004 
A6.3.4.3 Sulfate 
The areal distribution of sulfate (SO4
2) (Figure A6-16) has patterns similar to those described 
for Cl (Figure A6-15). 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/L, whereas 
SO4
2 concentrations west and east of Yucca Mountain are moderately to substantially higher. 
Borehole J-11 (Site 67) in central Jackass Flat has a SO4
2 concentration of 479 mg/L. 
Groundwater north of Yucca Mountain at Timber Mountain and in the upper part of Fortymile 
Wash near Rainer Mesa has SO4
2 concentrations in the same range as those found at Yucca 
Mountain. Groundwater SO4
2 concentrations north of the site model area increase toward Oasis 
Valley. The compositional differences between groundwater in western and eastern Crater Flat 
observed in Cl concentrations are also evident in SO4
2 concentrations, with the difference that 
the SO4
2 concentration at Gexa Well 4 (Site 68) in the northwest corner of the site model area 
more closely resembles groundwater in eastern Crater Flat at borehole VH-1 (Site 69) rather than 
western Crater Flat at borehole VH-2 (Site 70). 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. Unlike Cl, however, groundwater SO4
2 concentrations increase toward 
the south along Fortymile Wash. 
The groundwater with high Cl concentrations near the southwest corner of the site model area 
also has relatively high (100 to 200 mg/L) SO4
2 concentrations. Groundwater to the north of 
this area in western Crater Flat and to the northwest in southern Oasis Valley has similarly high 
SO4
2 concentrations. 
A6.3.4.4 Bicarbonate 
The areal distribution of bicarbonate (HCO3
) is shown in Figure A6-17. 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/L) 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/L. Groundwater near the 
Fortymile Wash drainage in the Amargosa Desert (FMW-S group) has much lower (less than 
160 mg/L) HCO3
 concentrations than groundwater in the surrounding areas in the GF, AR, and 
AR/FMW groups but has slightly higher HCO3
 concentrations than groundwater upgradient 
along Fortymile Wash (FMW-N group). 
Most groundwater in the TM group has HCO3
 concentrations of 170 mg/L or greater with the 
exception of Site 24 (well ER-EC-07) in Beatty Wash, which has a concentration (148.8 mg/L) 
similar to that typically found in northern Yucca Mountain (120 to 140 mg/L). The moderately 
high HCO3
 concentrations found in the Oasis Valley area increase southeastward along the 
Amargosa River toward the AR and AR/FMW group wells. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-105 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-16. Areal Distribution of Sulfate in Groundwater 
Groundwater in southwestern Crater Flat (CF-SW group) has higher HCO3
 than groundwater in 
the CF grouping. Bicarbonate concentrations at site NC-EWDP-7S (Site 71) are particularly 
high, possibly reflecting the location of this well in a paleospring deposit or evaporative effects 
associated with a shallow water table (Table A6-1). Groundwater in central Jackass Flats at 
borehole J-11 (Site 67), where the high SO4
2 was noted previously, has one of the lowest 
HCO3
- concentrations (82 mg/L) in the map area. Similarly low HCO3
 concentrations are found 
in some of the LW group wells to the southwest of borehole J-11. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-106 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-17. Areal Distribution of Bicarbonate in Groundwater 
A6.3.4.5 Fluoride 
Few data for F concentrations are available for the Yucca Mountain. (Figure A6-18). These 
data are consistent with the concentration distributions for other anions like Cl (Figure A6-15) 
in this area, with dilute concentrations found near Fortymile Wash and concentrations that 
increase to the west and east of the wash. Groundwater fluoride concentrations at Yucca 
Mountain have a variability that is comparable to the variability found in the Yucca Mountain 
region as a whole (Figure A6-18). The F concentrations in northern Yucca Mountain are low 
compared to other areas of Yucca Mountain. Relatively high F concentrations of 4.5 to 
13.0 mg/L are found in groundwater at several wells along Yucca Crest (YM-CR group), in the 
Solitario Canyon Wash (SWC) group, and in the carbonate aquifer at well p#1 (Sites 62 and 63). 
Groundwater along Fortymile Wash has F concentrations that generally vary between 1 and 
2 mg/L, with no systematic north-south variations evident. Groundwater in southwest Crater 
Flat has lower F concentrations than groundwater in eastern Crater Flat or in the NC-EWDP 
wells farther to the east. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-107 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-18. Areal Distribution of Fluoride in Groundwater 
A6.3.4.6 Silica 
Groundwater in northern and central Yucca Mountain has SiO2 concentrations that range 
from 30 to 60 mg/L (Figure A6-19). Groundwater beneath Fortymile Wash east of Yucca 
Mountain has SiO2 concentrations that are approximately 50 to 60 mg/L. Southward from Yucca 
Mountain and along Fortymile Wash, SiO2 concentrations in groundwater near the southern site 
model boundary increase abruptly. Relatively high SiO2 concentrations (65 to 90 mg/L) 
characterize groundwater throughout most of Amargosa Desert, except near the Gravity fault 
where SiO2 concentrations are considerably lower. Groundwater associated with carbonate rocks 
is typically more concentrated in most chemical species than groundwater in the volcanic rocks, 
except for SiO2 (Winograd and Thordarson 1975 [DIRS 101167], Table 8). High SiO2 
concentrations can also be traced southeastward from the Oasis Valley area through the 
northwest Amargosa Desert. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-108 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-19. Areal Distribution of Silica in Groundwater 
A6.3.4.7 Calcium 
The calcium (Ca2+) concentrations of groundwater at Yucca Mountain are generally less 
than 20 mg/L (Figure A6-20), except at borehole p#1 (Site 63), where groundwater from the 
carbonate aquifer has a concentration of 100 mg/L. Along the eastern edge of Crater Flat and in 
western Yucca Mountain, Ca2+ concentrations are less than 5 mg/L. The Ca2+ concentration is 
higher in western Crater Flat at borehole VH-2 (Site 70) than in eastern Crater Flat at borehole 
VH-1 (Site 69). 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 (Yucca 
Mountain-South group). The Ca2+ concentration is relatively high (82 mg/L) at borehole J-11 
(Site 67) in central Jackass Flats, where SO4
2 is also relatively high (Figure A6-16). The 
Ca2+ concentration along Fortymile Wash is between 10 to 20 mg/L east and northeast of Yucca 
Mountain and increases to values generally between 20 to 30 mg/L in the Amargosa Desert. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-109 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-20. Areal Distribution of Calcium in Groundwater 
The Ca2+ concentration increases to the west and the east of Fortymile Wash in the Amargosa 
Desert. Groundwater Ca2+ concentrations in the southwest corner of the site model area 
(Amargosa River group) are generally higher than Ca2+ concentrations in upgradient areas in 
western Crater Flat, west of Bare Mountain, and in the Oasis Valley. 
A6.3.4.8 Magnesium 
The areal distribution of magnesium (Mg2+) concentrations (Figure A6-21) display a pattern that 
is similar, in terms of relative concentrations, to that of Ca2+. Magnesium concentrations in 
groundwater at Yucca Mountain range from 0.1 to 1.6 mg/L, except at borehole p#1 where the 
Mg2+ concentration is 10 mg/L in the volcanic aquifer and 39 mg/L in the carbonate aquifer. The 
Mg2+ concentration in groundwater in western Crater Flat at borehole VH-2 (Site 70) is high 
(30 mg/L) compared to the concentration of 1.5 mg/L measured in groundwater at borehole 
VH-1 (Site 69). In Nye County-EWDP wells south and southeast of Crater Flat (SW Crater Flat 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-110 November 2004 
and Yucca Mountain-South groups), Mg2+ concentrations are quite variable with concentrations 
generally increasing to the northwest. Concentrations of Mg2+ are generally low (less than 
1.5 mg/L) at Timber Mountain and in upper Fortymile Canyon, but are generally between 2 and 
3 mg/L along the length of Fortymile Wash east of Yucca Mountain and in the Amargosa Desert. 
Magnesium concentrations on the east and west side of the Amargosa Desert are considerably 
higher with values typically between 5 and 20 mg/L. In the southwest corner of the model area 
(Amargosa River group), Mg2+ concentrations generally are between 5 to 10 mg/L, but a few 
samples have concentrations between 10 and 20 mg/L, similar to the concentration of 
groundwater at the sites 15 to 17 west of Bare Mountain (11.5 to 16 mg/L), but higher than those 
in Oasis Valley. The concentration of Mg2+ is 13 mg/L at borehole J-11 (Site 67) in central 
Jackass Flats. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-21. Areal Distribution of Magnesium in Groundwater 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-111 November 2004 
A6.3.4.9 Sodium 
The areal distribution of sodium (Na+) is shown in Figure A6-22. Excluding data from the 
carbonate aquifer (borehole p#1), the Na+ concentrations of groundwater at Yucca Mountain 
range between 46 and 130 mg/L with the higher values from samples in the western part of 
Yucca Mountain (Solitario Canyon Wash and Yucca Crest groups). A zone of relatively low 
Na+ concentrations (less than 60 mg/L) extends southeastward from northern Yucca Mountain 
toward lower Dune Wash and Fortymile Wash. The Na+ concentrations of groundwater in the 
NC-EWDP boreholes west of Fortymile Wash are generally between 40 and 100 mg/L, except at 
boreholes NC-EWDP-3D and NC-EWDP-3S (Sites 86 to 88) where the Na+ concentration was 
anomalously high (113 to 135 mg/L). The Na+ concentrations of groundwater at borehole 
NC-EWDP-5S (Site 154) west of the Striped Hills and at well J-11 (Site 67) in central Jackass 
Flats are also high (149 and 154 mg/L, respectively [Table A6-1]). Note that the value of 
149 mg/L at NC-EWDP-5S listed in Table A6-1 is obscured in Figure A6-22 by the somewhat 
lower value of 107 mg/L at nearby Site 155. Most of the groundwater samples along Fortymile 
Wash have Na+ concentrations between 35 and 50 mg/L; 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 (Amargosa River group) has high Na+ concentrations 
(130 to 180 mg/L), similar to those of sites 15 to 17 west of Bare Mountain and groundwater in 
Oasis Valley. 
A6.3.4.10 Potassium 
Potassium (Figure A6-23) concentrations in groundwater at Yucca Mountain range between 
1 and 6 mg/L, except in the carbonate aquifer at borehole p#1 (Site 63) where the 
K+ concentration is 12 mg/L. Groundwater from the Solitario Canyon and Yucca Crest groups 
typically has smaller K+ concentration when compared to groundwater farther east at 
Yucca Mountain in the FMW-N group. The K+ concentrations in groundwater in western Crater 
Flat at borehole VH-2 (Site 70) is high (8 mg/L). Similarly high K+ concentrations are found 
south of VH-2 in Nye County-EWDP wells 1S (Site 77) and 1DX (Site 73) and even higher 
concentrations exist at NC-EWDP-12PA (Site 78) and -12PB (Site 79). Concentrations of 
K+ are generally low (less than 5 mg/L) in northern Fortymile Canyon but are generally between 
5 and 8 mg/L along the length of Fortymile Wash east of Yucca Mountain and in the Amargosa 
Desert. In the eastern and western parts of the Amargosa Desert, K+ concentrations are typically 
higher than those in groundwater near the adjacent reach of Fortymile Wash. However, even 
among the FMW-S samples along Fortymile Wash, K+ concentrations are two to three times 
higher than K+ concentrations in upgradient areas in the southern Yucca Mountain (YM-S) 
group. Potassium concentrations in the Amargosa River (AR) group are similar to those of 
groundwater at Sites 15 through 17 west of Bare Mountain and somewhat higher than those 
found in Oasis Valley. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-112 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-22. Areal Distribution of Sodium in Groundwater 
A6.3.4.11 Delta Deuterium 
The areal distribution of delta deuterium (dD) values is shown in Figure A6-24 (this isotopic 
parameter is defined and discussed in Section A6.3.1.2). The dD values in groundwaters from 
the Yucca Mountain area range from about 105 per mil at borehole USW SD-6 (Site 50) to 
about 99 per mil at borehole G-2 (Site 43). In Crater Flat, the dD values of 108 and 106 per 
mil measured in water from borehole VH-1 (Site 69) and from Gexa Well 4 (Site 68) are 
substantially lighter (i.e., more negative) than the dD value of 99 per mil measured in 
groundwater from borehole VH-2 (Site 70), but similar to the extremely light values found in 
Oasis Valley and lower Beatty Wash. The dD values at borehole NC-EWDP-1DX (Site 73) 
of -101.3 per mil and at borehole NC-EWDP-3D (Site 86) of 105.6 per mil are generally similar 
to the values at upgradient boreholes VH-2 and VH-1 (99.5 and 108.0, respectively). The 
groundwater dD value of 98.0 per mil at Site 71 (NC-EWDP-7S) is also relatively heavy and 
comparable to the value at borehole VH-2. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-113 November 2004 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-23. Areal Distribution of Potassium in Groundwater 
The dD values of groundwater near Fortymile Wash show a general trend toward more depleted 
values from north to south, ranging from about 93 to 91 per mil at boreholes UE-29 a#1 and 
a#2 (Sites 3032) 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 
values of -104 per mil of groundwater at boreholes NC-EWDP-2D (Site 91)) and dD values 
of -110 to -104 per mil at well NC-EWDP-19D (Sites 92 and 9498) are substantially lighter 
than in groundwater associated with Fortymile Wash in the FMW-N group. Groundwater in the 
Amargosa Desert has variable values, and spatial patterns are not as regular as for other chemical 
species, but groundwater in the eastern part of the Amargosa Desert is generally lighter in dD 
than groundwater farther to the west near Fortymile Wash. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-114 November 2004 
Source: Table A6-2 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-24. Areal Distribution of Delta Deuterium in Groundwater 
Groundwater dD values at Timber Mountain are quite variable, ranging from 
about 114 to -96 per mil, with the heaviest value found in upper Beatty Wash at Site 24 (well 
ER-EC-07). The groundwater dD values near Oasis Valley are among the lightest in the vicinity 
of Yucca Mountain (116 to 108 per mil). Groundwater dD values lighter than 108 per mil 
are also found at sites 15 to 18 (Figure A6-5) west of Bare Mountain in the northwest Amargosa 
Desert. Southeast of these sites along the Amargosa River, groundwater from the AR and 
AR/FMW well groups has dD values that are typically heavier than values from wells to the 
northwest. 
A6.3.4.12 Delta Oxygen-18 
Figure A6-25 shows the areal distribution of delta oxygen-18 (d18O) values for the Yucca 
Mountain area (this isotopic parameter is defined and discussed in Section A6.3.1.2). 
Groundwater at Yucca Mountain has d18O values between 13.3 and 14.4 per mil, with 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-115 November 2004 
groundwater in western Yucca Mountain near Solitario Canyon having values that fall toward 
the lighter end of this range. Groundwater at borehole VH-1 (Site 69) in Crater Flat has a d18O 
value of 14.2 per mil, similar to the d18O value of 14.1 per mil of groundwater at Gexa Well 4 
(Site 68) and at Site 23 (well ER-OV-03c) in lower Beatty Wash. Groundwater in southwestern 
Crater Flat has substantially heavier d18O values, with groundwater at VH-2 (Site 70) having 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. However, the groundwater d18O value at site 
71 (NC-EWDP-7S) has a somewhat heavier d18O value than upgradient groundwater, perhaps 
reflecting the effects of evapotranspiration due to the shallow water table (7 m) at this well. 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-25. Areal Distribution of Delta Oxygen-18 in Groundwater 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-116 November 2004 
The groundwater d18O values at Sites 28 to 32 (Figure A6-5) in the FMW-N group are relatively 
heavy (12.8 to 11.8 per mil) compared to wells to the south within this group and to most 
groundwater in the FMW-S group (Table A6-2). (Note that the apparent range of values on 
Figure A6-25 is somewhat less because not all data are evident in the figure). Groundwater 
within the FMW-N group is distinctly heavier in d18O than groundwater to the west at Yucca 
Mountain. In the Amargosa Desert, the d18O of groundwaters 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. 
The groundwater d18O at Timber Mountain are generally lighter than most groundwater found at 
Yucca Mountain, except for groundwater found directly north of Yucca Mountain in upper 
Beatty Wash. Groundwater d18O values become lighter toward the west in Beatty Wash. 
Relatively light groundwater d18O values are found in Oasis Valley and in the northwest 
Amargosa Desert west of Bare Mountain at Sites 15 to 18. As with dD values, groundwater d18O 
increase downstream along the Amargosa River toward the AR and AR/FMW sites. 
A6.3.4.13 Delta Sulfur-34 
Groundwater data for delta 34S (d34S) were not collected from the Yucca Mountain area and 
Amargosa Desert before the late 1990s, nor have they been collected in areas north of Yucca 
Mountain. Consequently, areal coverage is not as complete as for most other ions and isotopes. 
The limited data from Yucca Mountain shows that groundwater from two wells along Yucca 
Crest have higher d34S values than groundwater in the YM-SE grouping near Dune Wash 
(Figure A6-26). Groundwater from wells in the CF-SW and YM-S groupings near 
U.S. Highway 95 generally show an overall increase toward the west. Groundwaters in the 
easternmost wells of the YM-S grouping (wells NC-EWDP-2D, NC-EWDP-19D, and 
NC-EWDP-19P) have d34S values that span a range similar to that defined by the groundwater 
samples from Yucca Crest and Dune Wash. In the Amargosa Desert, groundwater associated 
with the Amargosa River and the Gravity fault has substantially higher d34S values than 
groundwater associated with Fortymile Wash, perhaps reflecting the presence of alluvium 
derived from carbonate rocks in these areas. As discussed in Section A6.3.1.2.3, marine sulfates 
from the early Paleozoic have d34S values near 30 per mil, values that are considerably higher 
than the values of 0 to 15 typical of sulfur of a volcanic origin. Some of the lowest groundwater 
d34S values are found in Jackass Flat at well J-11 (Site 67) and in several of the LW-group wells 
in the Amargosa Valley area. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-117 November 2004 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-26. Areal Distribution of Delta Sulfur-34 in Groundwater 
A6.3.4.14 Delta Carbon-13 
The areal distribution of delta d13C values is shown in Figure A6-27 (this isotopic parameter is 
defined and discussed in Section A6.3.1.2). Excluding the data from borehole p#1 (Sites 62 
and 63), 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 (Sites 45 and 46) to 4.9 per mil at borehole H-3 
(Site 51). Although patterns are complex on a borehole-by-borehole basis, groundwater in the 
northern most part of Yucca Mountain is generally lighter in d13C than groundwaters found 
toward the central and southern parts of the mountain. North of Yucca Mountain, groundwater 
d13C values are generally considerably heavier than the groundwater d13C values found at 
Yucca Mountain. Only groundwater from well ER-EC-07 (Site 24) in Beatty Wash has a d13C 
within the range of values found at Yucca Mountain, in the Solitario Canyon Wash area, or in 
Crater Flat at borehole VH-1 (Site 69). Overall, the d13C values of groundwater in the Nye 
County-EWDP boreholes at the southern edge of Crater Flat increase toward the west, reflecting 
the increasing proximity of groundwater to carbonate rocks with relatively heavy d13C values. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-118 November 2004 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-27. Areal Distribution of Delta Carbon-13 in Groundwater 
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 lower than the d13C values toward 
the western and eastern parts of the Amargosa Desert, where groundwater d13C values reflect the 
proximity to carbonate rocks of the southern Funeral Mountains and discharge from the 
carbonate aquifer across the Gravity fault, respectively. Several of the d13C values of 
groundwater near the southwest corner of the site model area are similar to the values measured 
in groundwater at sites 15 to 18 west of Bare Mountain and in wells and springs in Oasis Valley. 
Groundwater in Jackass Flats and some groundwater at Amargosa Valley have relatively light 
d13C values, despite the proximity of the Amargosa Valley (LW) group to groundwater near the 
Gravity fault with considerably heavier d13C values. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-119 November 2004 
A6.3.4.15 Carbon-14 Activity 
The areal distribution of 14C activity in pmc is shown in Figure A6-28. This hydrochemical 
parameter is discussed in Section A6.3.1.2. Excluding groundwater from borehole p#1 
(Sites 62 and 63), 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 (Site 51) to 27 pmc at borehole WT-24 (Site 44) in northern Yucca Mountain. 
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 
(Site 42) and 10 pmc in a sample from borehole H-6 (Site 34). Groundwater 14C activities are 
slightly higher (12 pmc) farther to the west in Crater Flat at borehole VH-1 (Site 69). 
Groundwater at several Nye County-EWDP wells in the YM-S grouping to the south of borehole 
VH-1 has similar 14C activities. The groundwater at boreholes NC-EWDP-2D (Site 91), 
NC-EWDP-19P (Site 93), and some zones in NC-EWDP-19D (i.e. Site 96) have 14C activities 
of 20 pmc or more, similar to the 14C activities of groundwater in Dune Wash and Fortymile 
Wash. 
Groundwater near Fortymile Wash has 14C activities that range from about 76 pmc at borehole 
a#1 (Site 32) near the northern boundary of the model area to values less than 20 pmc near the 
southern boundary of the model area, with local reversals in this overall trend among the 
FMW-N group of samples. Southward from this area along Fortymile Wash, groundwater 14C 
activities are lower but also do not show an obvious north-to-south trend. South of the southern 
boundary of the site model area, groundwater 14C activities near Fortymile Wash range from 
10 to 40 pmc. Elsewhere in the Amargosa Desert, several groundwater 14C activities measured 
in the southwest corner of the site model area are approximately 30 pmc, which is considerably 
higher than the values of groundwater to the north and moderately higher than the values 
measured to the northwest at sites 15 to 18 west of Bare Mountain and in Oasis Valley. 
In general, it can be noted that where relatively high groundwater d13C values indicate 
water/rock interactions with isotopically heavy carbonate rock (Figure A6-27), the groundwater 
14C activities are generally low compared to other areas. These carbonate-rock-affected 
groundwaters are present at Timber Mountain, near Bare Mountain in the CF-SW area, near the 
southern Funeral Mountains in some AR and AR/FMW groundwaters, and near the GF samples. 
The highest 14C activities are associated with major drainages, including the Amargosa River in 
the southwest corner of the site model area, upper Beatty Wash, and along Fortymile Wash, 
suggesting that these major washes are important areas of Holocene recharge. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-120 November 2004 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-28. Areal Distribution of Carbon-14 in Groundwater 
A6.3.4.16 Uranium Concentration and 234U/238U Activity Ratios 
Uranium concentration and 234U/238U activity ratio data are shown in Figures A6-29 and A6-30 
respectively. Processes affecting uranium concentrations and 234U/238U activity ratios are 
discussed in Section A6.3.1.2 and in Paces et al (2002 [DIRS 158817]). Some of the highest 
activity ratios in the region are found at Timber Mountain (TM group) and in northern and 
southeastern Yucca Mountain (YM-CR and YM-SE groups). Samples in the YM-CR and 
YM-SE with these elevated 234U/238U activity ratios also have relatively small uranium 
concentrations (less than 2.5 g/L, but most approximately 1 g/L), whereas groundwaters from 
the TM group (except for Site 24 in upper Beatty Wash) have somewhat higher uranium 
concentrations (Figure A6-29). In addition to different uranium concentrations, other 
hydrochemical attributes of the Timber Mountain and Yucca Mountain groundwaters, such as 
Na+ (Figure A6-22), HCO3
 (Figure A6-17), and d13C (Figure A6-27), are also generally 
different, suggesting the groundwaters from these areas are not necessarily related, despite their 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-121 November 2004 
similar 234U/238U activity ratios. Data from borehole p#1 (Site 63) at Yucca Mountain indicate 
the carbonate aquifer has comparatively high uranium concentrations (13.3 g/L) and low 
234U/238U activity ratios (2.3) compared to some shallow groundwater at Yucca Mountain. 
Uranium activity ratios decrease southward along Fortymile Wash from a value as high as 7 at 
well J-13 (Site 35) to values below 3.0 in the northern Amargosa Desert. Paces et al (2002 
[DIRS 158817], p. 769) suggested that significant groundwater pumping from well J-13 and 
nearby well J-12 (Site 36) may have disrupted natural flow patterns and induced Yucca 
Mountain groundwater with high 234U/238U activity ratios to flow eastward toward Fortymile 
Wash. Measurements of archived water samples from well J-12 indicated its 234U/238U activity 
ratio in 1971 was 5.5, supporting the authors contention that the 234U/238U activity ratios at well 
J-13 may have initially been lower than recent measurement at that well have indicated. 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-29. Areal Distribution of Uranium in Groundwater 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-122 November 2004 
Uranium concentrations and 234U/238U activity ratios in the Amargosa Desert region have a 
relatively narrow range with concentrations typically between 1 and 4 g/L and activity ratios 
mostly between 2.5 and 3.5. Borehole NC-EWDP-5S (Site 154) has an anomalously high 
234U/238U activity ratio for this location of 6.6 and a very low uranium concentration of 
0.04 g/L. From east to west of Yucca Mountain through the Crater Flat area into the Oasis 
Valley, 234U/238U activity ratios generally decrease whereas uranium concentrations increase. 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-30. Areal Distribution of 234U/238U Activity Ratios (AR) in Groundwater 
A6.3.4.17 Strontium Concentrations and Delta Strontium-87 
Strontium concentrations from groundwater at Yucca Mountain vary considerably with values 
between 1.0 and 1720 g/L; most values, however, are between 10 and 50 g/L. In general, 
groundwater near Fortymile Wash has lower Sr2+ concentrations than groundwater to the east or 
west of the wash. Strontium concentrations in the FMW-N group are low (values mostly less 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-123 November 2004 
than 50 g/L) relative to those in the FMW-S group (most values greater than 100 g/L). 
Sr2+ concentrations in Beatty Wash are one-to-two orders of magnitude higher that 
Sr2+ concentrations in northern Yucca Mountain in the YM-CR group, which are among the 
lowest in the region. Groundwater from p#1(c) has a relatively high Sr2+ concentration of 
450 g/L. Similarly high values also characterize groundwater that is likely to have contacted 
Paleozoic carbonate rocks elsewhere in the area (e.g., samples from SW Crater Flat, Gravity 
fault, Funeral Mountains, and Amargosa Flat groupings). Groundwater in the Timber Mountain 
area has Sr2+ concentrations between about 99 and 224 g/L. 
Strontium isotope-ratio data (expressed as d87Sr) are unevenly distributed throughout the area 
with numerous values to the north of Yucca Mountain, some in the Yucca Mountain area and 
along U.S. Highway 95, and none in the Amargosa Desert region. Very low d87Sr values are 
found in groundwater in Beatty Wash, in the Timber Mountain area, and in Oasis Valley (less 
than 1.8 per mil, with some negative values). Generally higher values exist to the south of the 
TM and upper FMW-N groups, although some Yucca Mountain groundwaters also have 
comparably low d87Sr values. Interestingly, d87Sr values of groundwater from the carbonate 
aquifer or from boreholes that have a component of water from the carbonate aquifer (e.g. 
p#1(c), SW Crater Flat, Funeral Mountains) have high d87Sr. These waters also typically have 
high strontium concentrations. Reaction with the Paleozoic carbonate aquifer rock cannot 
explain this trend as these rocks are expected to have d87Sr values of less than zero. A possible 
explanation is that these waters have reacted with Paleozoic or Precambrian clastic rocks, which 
are expected to have high d87Sr due to their composition and age of the original detrital material 
(Peterman and Stuckless 1993 [DIRS 101149], p. 1561). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-124 November 2004 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-31. Areal Distribution of Strontium in Groundwater 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-125 November 2004 
Source: Table A6-2. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-32. Areal Distribution of Delta Strontium-87 in Groundwater 
A6.3.5 Areal Distribution of Calculated Geochemical Parameters 
The following subsections describe the areal distribution of the calculated geochemical 
parameters, including a brief summary of how the calculated parameters would be expected to 
reflect the relative state of evolution of the groundwater. A number of geochemical parameters 
were calculated with PHREEQC V2.3, STN: 10068-2.3-00 (BSC 2001 [DIRS 155323]: 
Parkhurst and Appelo 1999 [DIRS 159511]) to further characterize groundwater in the Yucca 
Mountain area. These parameters include charge balance error, ionic strength, dissolved 
inorganic carbon (DIC), the logarithm of dissolved carbon-dioxide partial pressure (log PCO2), 
and the saturation indices of many minerals identified at Yucca Mountain (Table A6-3 below). 
The charge-balance errors are helpful in evaluating the reliability of hydrochemical analyses 
given in Table A6-1 of this report. The calculated DIC concentrations are used for evaluating 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-126 November 2004 
the extent of calcite dissolution Yucca Mountain recharge undergoes as it moves through the 
saturated zone (Section A6.3.6.6) and in mixing models involving 14C (Sections A6.3.6.7 
and A7.3.6). The saturation indices are used to help constrain the possible reactions in inverse 
mixing and water/rock interaction models presented in Section A6.3.8. 
The saturation indices of many common minerals such as K-feldspar, amorphous silica [SiO2(a)], 
and calcite were based on thermodynamic data contained in the phreeqc.dat database provided 
with PHREEQC (Parkhurst and Appelo 1999 [DIRS 159511] Table 55). In addition, the specific 
chemical formulas and thermodynamic data for Ca- and Na-clinoptilolite and smectite that have 
been identified at Yucca Mountain were used in PHREEQC to compute saturation indices. The 
chemical formulas of these minerals and the Gibbs free-energies (.GO
f) and enthalpies (..O
f) of 
formation estimated for these minerals are listed in Table A6-4. 
For the purpose of calculating mineral saturation indices, when field temperature measurements 
are unavailable, the temperature of groundwater samples was approximated either from 
published maps of water table temperatures at Yucca Mountain or, in the Amargosa Desert, was 
assumed to be 25C. The use of a contour map of water table temperatures (Fridrich et al. 1994 
[DIRS 100575], Figure 8) to estimate groundwater sample temperatures at Yucca Mountain is 
an acceptable approximation because most of the samples for which this approximation was 
made are from the upper part of the saturated zone (Figure 6.7-2 samples 33, 34, 41, 57, 
and 66). Likewise, the assumption that groundwater samples in the Amargosa Desert with no 
measured temperatures are at 25C is an acceptable approximation because most of the measured 
groundwater sample temperatures are in the range of 25 to 30C (see data for LW, FMW-S, 
FMW-E, FMW-W, GF, AR, and AR/FMW sample groups in Table A6-1. 
The calculation of saturation indices for alumino-silicate minerals such as those listed in 
Table A6-4 requires measurements of dissolved Al3+ concentrations in the groundwater. 
Although recent groundwater samples from the Yucca Mountain area have reported dissolved 
Al3+ concentrations, historic data from the Yucca Mountain area are generally lacking this 
information. To get an estimate of the saturation indices of alumino-silicate minerals throughout 
the Yucca Mountain area, dissolved Al3+ concentrations for each sample were assumed to be in 
equilibrium with kaolinite (see Table A5-1, Assumption 2). This assumption provides estimates 
of dissolved Al3+ concentrations that are in good agreement with measured Al3+ concentrations at 
sites where these data are available (Figure A6-33). Estimates of Al concentrations made by 
assuming groundwater equilibrium with other Al3+-bearing minerals such as gibbsite, smectite, 
clinoptilolite, and K-feldspar did not produce nearly as good a match to the available Al3+ data. 
Other factors affecting the calculated saturation indices are discussed in Section A7.3.2. These 
factors include uncertainty in thermodynamic data use to calculate the mineral solubility 
constants, variability in mineral compositions and particle sizes, and slow reaction rates relative 
to the groundwater residence times. 
MDL-NBS-HS-000011 REV 02 A-127 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report 
Mineral Saturation Indices2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Oasis Valley/NW Amargosa 
ER-EC-08 1 7.18x10-3 -3.5 176.8 -2.68 -0.06 4.00 16.11 -0.49 -0.53 -1.51 -0.65 -0.73 
ER-OV-01 2 7.43x10-3 1.3 197.2 -3.02 -0.10 6.16 29.11 -0.24 -1.43 -0.80 0.22 -1.64 
ER-OV-06a 3 7.46x10-3 0.8 201.0 -2.99 -0.53 5.32 23.90 -0.39 -1.59 -1.04 -0.03 -1.14 
ER-OV-05 4 7.27x10-3 0.2 241.5 -2.46 -0.01 6.81 31.43 -0.13 -1.01 -1.25 0.11 -0.41 
ER-OV-02 5 8.24x10-3 -0.2 226.6 -2.90 0.12 6.80 30.85 -0.26 -0.91 -1.03 -0.16 -0.87 
Springdale Upper Well 
(10S/47E-32adc) 6 8.51x10-3 -0.3 303.0 -2.26 0.00 6.31 27.98 -0.21 -0.86 -1.40 -0.22 -0.41 
Goss Springs North 
(11S/47E-10bad) 7 6.88x10-3 -1.6 179.7 -3.01 0.08 6.88 31.04 -0.29 -0.77 -1.22 -0.12 -0.72 
Er-OV-03a 8 7.02x10-3 1.1 184.6 -2.90 -0.08 6.90 30.91 -0.27 -0.87 -1.25 -0.17 -1.06 
ER-OV-03a3 9 7.19x10-3 0.5 182.0 -3.08 0.14 6.47 29.69 -0.31 -1.03 -1.05 0.01 -0.50 
ER-OV-03a2 10 2.06x10-2 -3.0 241.6 -3.92 0.54 5.39 26.20 -0.81  -0.76 1.05 0.64 
Goss Spring (11S/47E- 
10bcc) 
11 7.21x10-3 1.4 187.6 -2.47 -0.32 6.04 24.88 -0.34 -0.67 -1.73 -0.71 -1.46 
ER-OV-04a 12 5.71x10-3 0.2 162.7 -3.21 0.06 6.46 30.96 -0.23 -0.97 -0.86 0.40 -1.48 
Beatty Well no. 1 
(Wat&Sanit Distr) 13             
Bond Gold Mining #1 14 5.90x10-3 -2.4 158.7 -3.12 0.39 5.10 20.82 -0.62 -1.91 -1.89 -0.50 0.55 
US Ecology MW-313 15 1.42x10-2 -6.0 355.2 -2.00 0.18 6.08 26.48 -0.23 0.16 -1.59 -0.30 0.18 
US Ecology MW-600 16 1.18x10-2 -4.0 300.4 -2.45 0.12 6.04 27.07 -0.28 -0.20 -1.21 -0.15 0.34 
Nucl. Eng. Co. Well 17 1.43x10-2 -0.1 342.4 -2.11 0.28 6.15 27.23 -0.22  -1.40 -0.28 0.32 
US Ecology MR-3 18             
MDL-NBS-HS-000011 REV 02 A-128 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
Mineral Saturation Indices2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Timber Mountain 
UE-18r 19 4.84x10-3 0.0 211.2 -2.85 0.42 5.01 21.03 -0.44 -0.73 -1.50 -0.66 -0.17 
ER-18-2 20 1.54x10-2 5.3 755.1 -1.55 0.02 1.65 2.43 -0.67 -0.29 -1.64 -1.68 -0.91 
ER-EC-05 21 4.84x10-3 6.5 144.8 -2.82 0.09 4.78 18.13 -0.50 -0.20 -1.84 -1.19 -0.95 
Coffer's Ranch Windmill 
Well 22 4.63x10-3 -1.4 182.4 -3.08 0.26 6.11 25.06 -0.43 -0.45 -1.55 -1.04 -1.10 
ER-OV-03c 23 5.03x10-3 0.1 160.8 -3.02 0.10 5.90 24.21 -0.42 -0.28 -1.54 -0.95 -1.07 
ER-EC-07 24 3.69x10-3 -2.9 150.6 -2.70 0.06 4.86 18.66 -0.47 -1.13 -2.17 -0.96 -0.58 
Fortymile WashNorth 
Water Well 8 25 2.26x10-3 2.6 86.1 -2.40 -1.29 5.51 19.66 -0.36 -2.12 -2.70 -1.32 -3.06 
Test Well 1 (USGS HTH 
#1) 
26 2.29x10-3 7.7 99.6 -3.70 -0.60 4.15 13.12 -0.82  -1.97 -1.66  
UE-18t 27 8.09x10-3 0.5 320.8 -3.12 0.93 3.21 7.90 -1.25  -2.52 -1.41 0.89 
ER-30-1 (upper) 28 3.17x10-3 4.4 108.9 -4.43 0.43 5.26 23.32 -0.72 -1.78 -1.04 -0.21 -0.34 
ER-30-1 (lower) 29 3.04x10-3 7.1 113.2 -4.18 0.09 4.86 19.81 -0.76 -2.17 -1.27 -0.73 -0.79 
a#2 (dp) 30 2.96x10-3 -2.3 121.0 -2.16 -1.16 5.14 16.23 -0.42 -1.74 -2.76 -2.03 -3.66 
a#2 (sh) 31 2.92x10-3 -0.3 130.2 -1.98 -1.39 5.39 16.75 -0.40 -1.80 -2.95 -2.12 -3.98 
UE-29a#1 HTH 32 3.09x10-3 5.2 114.1 -2.57 -0.61 6.04 24.28 -0.29 -1.98 -2.21 -0.80 -1.71 
WT#15 33 3.95x10-3 2.3 175.2 -2.23 -0.50 4.55 16.64 -0.42  -2.20 -1.08 -1.42 
WT#14 34 3.11x10-3 0.2 130.5 -2.19 -0.95 4.97 18.11 -0.35  -2.45 -1.12 -2.59 
J-13 35 3.23x10-3 0.3 139.0 -2.06 -0.94 4.82 16.97 -0.36 -0.97 -2.58 -1.23 -2.22 
J-12 36 3.29x10-3 -1.3 138.1 -2.01 -1.04 5.22 18.33 -0.35 -0.98 -2.75 -1.31 -2.54 
JF#3 37 3.78x10-3 1.3 123.8 -2.61 -0.36 5.60 23.21 -0.33 -1.12 -2.13 -0.44 -1.11 
MDL-NBS-HS-000011 REV 02 A-129 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
Mineral Saturation Indices2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Solitario Canyon Wash 
H-6(bh) 38 4.41x10-3 -0.8 181.1 -2.76 -0.30 3.93 14.51 -0.50 -0.97 -1.57 -1.20 -1.75 
H-6(Tct) 39 4.52x10-3 -6.6 212.4 -2.87 -0.47 3.43 12.50 -0.55 -1.65 -1.41 -1.09  
H-6(Tcb) 40 4.97x10-3 -9.5 229.7 -2.87 0.03 4.10 16.23 -0.49 -0.93 -1.35 -0.95 -1.15 
WT-7 41 4.76x10-3 -2.5 241.0 -3.27 0.13 3.31 10.76 -0.88  -1.73 -1.16 -0.39 
WT-10 42 4.64x10-3 1.4 180.3 -3.06 -0.21 3.84 14.76 -0.53 -1.40 -1.28 -1.08 -1.36 
Yucca MountainCrest 
G-2 43 2.89x10-3 0.6 127.6 -2.35 -0.79 4.35 15.53 -0.44 -1.95 -2.35 -1.05 -2.33 
USW WT-24 44 2.73x10-3 2.4 120.9 -2.82 -1.93 5.49 21.06 -0.35 -3.34 -1.78 -1.01  
UZ-14(sh) 45 3.41x10-3 8.1 129.2 -3.29 -1.41 5.31 21.74 -0.45 -1.69 -1.35 -0.61 -2.95 
UZ-14(dp) 46 3.53x10-3 6.3 133.8 -3.26 -1.55 5.14 21.26 -0.43 -1.84 -1.29 -0.50 -3.04 
H-1(Tcp) 47 2.78x10-3 0.6 118.5 -2.58 -0.86 4.40 15.47 -0.46 -2.01 -2.17 -1.25 -2.95 
H-1(Tcb) 48 2.93x10-3 -0.7 125.7 -2.55 -0.68 3.96 12.49 -0.55 -2.05 -2.32 -1.60 -2.71 
H-5 49 2.92x10-3 2.1 127.8 -2.73 -0.95 4.08 14.59 -0.48 -2.26 -1.90 -1.14  
USW SD-6 50 4.35x10-3 -0.7 182.1 -3.08 -1.05 4.16 16.13 -0.51 -1.96 -1.30 -0.86  
H-3 51 6.12x10-3 -3.7 240.9 -3.85 -0.09 5.23 23.60 -0.55 -1.55 -0.57 -0.28  
Yucca MountainCentral 
G-4 52 3.56x10-3 3.7 143.0 -2.49 -0.31 4.07 13.89 -0.50 -0.96 -2.18 -1.39 -1.98 
b#1(Tcb) 53 3.59x10-3 2.0 152.4 -1.89 -0.76 3.85 11.12 -0.46 -1.22 -2.76 -1.78 -2.47 
b#1(bh) 54 3.94x10-3 -3.4 170.1 -2.03 -0.51 4.13 13.61 -0.44 -1.22 -2.50 -1.43 -1.99 
H-4 55 4.58x10-3 3.9 185.2 -2.10 -0.42 4.11 13.31 -0.48 -0.33 -2.34 -1.57 -2.16 
UZ#16 56 5.79x10-3 10.8 185.9 -3.75 0.85   -0.62  -1.05  2.27 
MDL-NBS-HS-000011 REV 02 A-130 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
Mineral Saturation Indices2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Yucca MountainSoutheast 
ONC#1 57 3.40x10-3 9.1 107.8 -3.64 0.49 4.24 16.99 -0.72  -1.72 -0.60 0.33 
c#1 58 3.63x10-3 -3.4 156.6 -2.31 -0.37 3.61 12.00 -0.45 -1.25 -2.12 -1.41 -1.82 
c#3 59 3.48x10-3 0.2 140.5 -2.46 -0.32 3.65 12.34 -0.47 -1.28 -2.07 -1.37 -1.60 
c#3(95-97) 60 3.43x10-3 3.6 144.5 -2.45 -0.30 3.78 13.30 -0.43  -1.98 -1.29 -1.69 
c#2 61 3.53x10-3 -0.2 142.5 -2.45 -0.28 3.72 12.85 -0.46 -1.20 -2.06 -1.31 -1.56 
p#1(v) 62 8.25x10-3 -1.2 438.7 -1.14 -0.32 2.90 6.20 -0.53 -0.44 -2.83 -1.93 -0.72 
p#1(c) 63 1.85x10-2 -2.5 976.6 -0.58 0.22 1.35 -1.76 -0.68 -0.02 -3.04 -2.14 0.53 
WT-17 64 3.15x10-3 -1.0 150.1 -1.96 -1.18 4.50 13.04 -0.51 -1.23 -2.93 -1.91 -2.96 
WT#3 65 3.37x10-3 -1.2 144.3 -2.41 -0.52 4.83 18.44 -0.37 -1.05 -2.13 -0.97 -1.66 
WT#12 66 4.30x10-3 0.1 174.0 -2.33 -0.31 4.43 15.67 -0.46 -0.71 -2.16 -1.32 -1.90 
Jackass Flats 
J-11 67 1.69x10-2 1.4 80.6 -3.23 0.24 6.09 28.57 -0.31 -1.00 -1.13 0.25 0.10 
Crater Flat 
GEXA Well 4 68 4.56x10-3 -2.3 151.8 -2.69 -0.21 4.72 18.48 -0.45 -0.80 -1.82 -0.89 -1.46 
VH-1 69 4.77x10-3 0.9 171.3 -2.32 -0.47 4.18 14.35 -0.46 -1.03 -2.05 -1.45 -1.33 
Crater FlatSouthwest 
VH-2 70 1.29x10-2 -1.3 446.9 -1.48 0.14 3.60 8.75 -0.71 -1.08 -3.15 -1.85 0.28 
NC-EWDP-7S 71 1.44x10-2 -0.6 461.8 -1.73 0.19 4.96 15.69 -0.68 -1.06 -2.95 -1.59 0.37 
NC-EWDP-7SC 72 1.50x10-2 -0.4 480.4 -1.60 0.18 4.47 12.52 -0.69 -1.17 -3.01 -2.00 0.36 
NC-EWDP-1DX 73 1.19x10-2 -3.5 414.1 -1.66 -0.03 5.42 20.19 -0.40 -1.52 -2.51 -1.04 0.03 
NC-EWDP-1DX Zone 2 74 2.09x10-2 -9.3 1385.6 -0.70 -0.26 4.86 15.91 -0.38 0.62 -2.30 -1.72 -0.70 
NC-EWDP-01S Zone 1 75 1.15x10-2 -3.7 386.1 -1.86 0.20 5.39 21.01 -0.38 -1.65 -2.30 -0.84 0.49 
NC-EWDP-01S Zone 2 76 1.14x10-2 -3.8 389.0 -1.75 0.09 5.17 19.40 -0.40 -1.68 -2.44 -0.99 0.30 
MDL-NBS-HS-000011 REV 02 A-131 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
MINERAL SATURATION INDICES2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Crater FlatSouthwest (Continued) 
NC-EWDP-01S 77 1.16x10-2 -1.9 390.9 -1.75 0.12 5.32 20.60 -0.35 -1.66 -2.31 -0.90 0.34 
NC-EWDP-12PA 78 1.10x10-2 -1.6 540.6 -1.18 -0.58 5.37 20.88 -0.25 -0.25 -2.28 -0.71 -1.35 
NC-EWDP-12PB 79 1.08x10-2 -1.7 491.4 -1.29 -0.48 5.28 20.77 -0.27 -0.23 -2.21 -0.64 -1.15 
NC-EWDP-12PC 80 1.09x10-2 0.0 340.5 -1.99 0.25 5.31 21.52 -0.35 -1.26 -2.08 -0.64 0.60 
Yucca MountainSouth 
NC-EWDP-09SX 81 6.32x10-3 -1.1 213.3 -2.67 0.21 5.33 22.48 -0.39 -0.89 -1.62 -0.57 0.37 
NC-EWDP-9SX Zone 1 82 5.95x10-3 -1.6 194.5 -3.02 0.37 5.41 23.28 -0.48 -0.92 -1.53 -0.35 0.62 
NC-EWDP-9SX Zone 2 83 6.01x10-3 -2.3 206.4 -2.59 0.03 5.20 20.88 -0.44 -0.96 -1.86 -0.76 0.04 
NC-EWDP-9SX Zone 3 84 5.94x10-3 -3.2 206.8 -2.78 0.22 5.20 21.43 -0.47 -0.93 -1.72 -0.64 0.44 
NC-EWDP-9SX Zone 4 85 5.95x10-3 -3.8 209.9 -2.68 0.15 5.23 21.43 -0.43 -0.96 -1.75 -0.71 0.28 
NC-EWDP-03D 86 5.63x10-3 -1.8 230.1 -2.99 -0.90 4.52 19.24 -0.43 -2.31 -1.06 -0.40 -2.05 
NC-EWDP-3S Zone 2 87 6.27x10-3 -0.7 234.5 -3.30 -0.45 4.97 22.47 -0.40 -2.09 -0.66 -0.26 -1.36 
NC-EWDP-3S Zone 3 88 6.90x10-3 -3.9 279.9 -3.44 -0.22 4.67 21.29 -0.51 -1.85 -0.67 -0.07 -0.89 
CIND-R-LITE 89 5.26x10-3 -2.0 195.9 -2.35 0.04 2.69 8.92 -0.53 -1.18 -1.88 -1.08 0.29 
NC-EWDP-15P 90 5.02x10-3 -1.0 192.2 -2.50 -0.30 4.95 19.33 -0.42 -1.17 -1.83 -0.94 -0.81 
NC-EWDP-02D 91 3.74x10-3 -2.9 158.2 -2.33 -0.45 5.52 20.90 -0.38 -1.07 -2.39 -1.06 -1.76 
NC-EWDP-19D 92 5.31x10-3 -0.4 233.7 -3.31 -0.10 5.36 25.23 -0.36 -1.96 -0.69 0.11 -1.03 
NC-EWDP-19P 93 3.40x10-3 -1.9 115.4 -3.62 0.53 5.52 25.93 -0.38 -1.22 -1.13 0.09 0.26 
NC-EWDP-19D (alluvial) 94 4.88x10-3 -2.6 228.2 -3.22 -0.08 5.17 23.71 -0.39 -1.84 -0.88 -0.07 -0.79 
NC-EWDP-19D (zone #1) 95 4.63x10-3 0.4 204.5 -3.26 0.10 5.08 23.52 -0.39 -1.72 -0.90 -0.03 -0.45 
NC-EWDP-19D (zone #2) 96 3.77x10-3 1.9 149.8 -3.11 0.13 5.54 24.92 -0.33 -1.33 -1.29 -0.20 -0.37 
NC-EWDP-19D (zone #3) 97 4.78x10-3 0.5 212.1 -3.15 -0.44 5.08 22.61 -0.40 -2.16 -0.99 -0.21 -1.58 
NC-EWDP-19D (zone #4) 98 5.20x10-3 -0.8 234.4 -3.51 -0.22 5.14 24.52 -0.40 -2.11 -0.56 0.21  
MDL-NBS-HS-000011 REV 02 A-132 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
MINERAL SATURATION INDICES2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Amargosa Valley 
NC-EWDP-4PB 99 3.98x10-3 -0.9 113.6 -4.53 0.78 5.18 23.61 -0.73 -1.56 -0.90 -0.10  
NC-EWDP-4PA 100 3.91x10-3 -0.4 107.8 -3.18 -0.11 5.25 20.58 -0.56 -1.51 -1.95 -0.88 -1.51 
Desert Farms Garlic Plot 101 6.54x10-3 0.0 127.7 -2.71 -0.09 5.22 20.39 -0.48 -1.58 -2.06 -0.88 -0.99 
15S/49E-13dda 102             
15S/50E-18ccc 103 6.35x10-3 -1.0 153.5 -3.23 0.32 5.32 22.38 -0.55 -0.97 -1.50 -0.53 -0.54 
NDOT 104 6.76x10-3 -0.4 161.0 -2.80 -0.04 5.22 21.28 -0.45 -1.11 -1.64 -0.75 -1.03 
15S/50E-18cdc 105 6.16x10-3 -3.5 158.4 -2.81 -0.20 5.15 19.90 -0.54 -1.20 -1.88 -0.92 -1.44 
Airport Well 106 3.93x10-3 0.0 121.5 -3.61 0.12 5.08 21.47 -0.54 -1.56 -1.28 -0.63 -1.14 
15S/50E-19b1 107 7.69x10-3 1.5 167.5 -2.90 0.10 5.72 24.44 -0.43 -1.26 -1.52 -0.42 -0.18 
Amargosa River 
16S/48E-8ba 108 1.42x10-2 1.4 299.8 -2.46 0.56 5.42 22.83 -0.49  -1.61 -0.42 0.49 
16S/48E-7bba 109 1.23x10-2 0.8 269.6 -2.02 -0.03 6.09 25.98 -0.23  -1.69 -0.48 -0.47 
16S/48E-7cbc 110 1.21x10-2 0.8 246.8 -2.35 0.18 6.16 27.12 -0.25  -1.49 -0.28 0.24 
16S/48E-18bcc 111 1.30x10-2 1.7 272.1 -2.60 0.60 6.48 30.96 -0.17  -0.95 0.28 0.84 
16S/48E-17ccc 112 1.47x10-2 3.4 246.3 -2.35 0.31 6.34 29.10 -0.18  -1.21 -0.02 0.19 
16S/48E-18dad 113 1.25x10-2 3.1 243.3 -2.35 0.24 6.32 28.73 -0.18  -1.27 -0.08 0.02 
16S/48E-8cda 114 1.25x10-2 1.2 276.1 -2.21 0.12 6.32 27.88 -0.22  -1.44 -0.28 -0.28 
16S/48E-17abb 115 1.33x10-2 0.8 324.8 -1.95 0.08 6.31 27.59 -0.18  -1.57 -0.33 -0.39 
Barrachman Dom/Irr. 116 1.26x10-2 -4.2 304.4 -2.10 0.04 6.83 29.73 -0.20 -0.63 -1.65 -0.35 -0.29 
McCracken Domestic 117 1.71x10-2 3.2 257.3 -2.17 0.16 6.64 29.58 -0.18 -0.57 -1.40 -0.23 -0.22 
MDL-NBS-HS-000011 REV 02 A-133 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
MINERAL SATURATION INDICES2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Fortymile WashWest 
16S/48E-15ba 118 1.30x10-2 -0.2 265.4 -2.61 0.62 5.42 22.86 -0.50  -1.62 -0.45 0.71 
16S/48E-10cba 119 4.25x10-3 -0.9 163.3 -3.10 0.03 6.21 28.67 -0.27  -1.22 0.08 0.04 
16S/48E-15aaa 120 3.95x10-3 1.7 152.8 -2.92 -0.15 6.10 27.61 -0.25  -1.39 -0.04 -0.43 
Selbach Domestic 121 7.48x10-3 -0.9 178.9 -2.77 0.10 6.33 28.77 -0.23 -1.19 -1.29 -0.08 0.08 
16S/48E-15dda 122 5.41x10-3 6.8 176.5 -2.77 0.10 6.26 28.59 -0.22  -1.35 0.01 0.00 
16S/49E-23add 123 4.02x10-3 7.5 125.0 -3.11 0.07 6.39 30.06 -0.19  -1.20 0.21 -0.48 
16S/48E-23bdb 124 3.97x10-3 3.0 172.3 -2.11 -0.97 6.12 24.99 -0.19  -2.04 -0.68 -2.56 
16S/48E-23da 125             
Funeral Mountain Ranch 
Irrig. 126 5.29x10-3 -2.0 198.4 -2.93 0.08 6.94 33.28 -0.11 -0.97 -0.93 0.39 -0.22 
Fortymile WashSouth 
16S/49E-05acc 127 4.07x10-3 5.0 134.3 -2.98 0.26 6.09 27.16 -0.28 -1.31 -1.68 -0.18 -0.24 
16S/49E-8abb 128 4.42x10-3 2.2 161.4 -2.33 -0.29 5.96 23.69 -0.32  -2.36 -0.82 -1.30 
16S/49E-8acc 129 3.91x10-3 1.4 139.7 -2.76 -0.01 5.83 25.07 -0.31  -1.91 -0.33 -0.64 
16S/49E-18dc 130 4.05x10-3 0.5 149.7 -2.93 0.15 6.03 27.13 -0.30  -1.65 0.02 -0.22 
16s/48E-24aaa 131 4.06x10-3 3.5 146.1 -2.93 0.12 6.15 28.67 -0.20  -1.29 0.13 -0.80 
16S/49E-19daa 132 3.92x10-3 0.1 131.9 -3.08 0.29 6.22 29.24 -0.21  -1.41 0.27 -0.35 
DeLee Large Irrigation 133 3.85x10-3 2.5 136.6 -2.94 -0.06 7.79 36.15 -0.10 -1.16 -1.54 0.29 -1.25 
16S/48E-25aa 134 3.73x10-3 0.6 132.1 -2.98 0.10 6.10 28.06 -0.23  -1.47 0.09 -0.87 
16S/48E-36aaa 135 3.56x10-3 0.1 128.3 -3.30 0.31 6.50 31.26 -0.19  -1.13 0.41 0.03 
Bray Domestic 136 3.75x10-3 0.9 131.8 -2.91 -0.01 6.87 31.56 -0.17 -1.37 -1.61 0.18 -0.82 
Amargosa Estates #2 137 3.68x10-3 1.4 133.3 -2.99 0.09 6.56 30.50 -0.17 -1.04 -1.43 0.17 -0.45 
17S/48E-1ab 138 3.65x10-3 1.2 134.1 -2.98 0.08 6.42 29.84 -0.18  -1.42 0.17 -0.58 
17S/49E-7bb 139 4.37x10-3 2.8 149.5 -3.14 0.42 6.52 31.32 -0.18  -1.14 0.39 0.04 
MDL-NBS-HS-000011 REV 02 A-134 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
MINERAL SATURATION INDICES2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Fortymile WashSouth (Continued) 
17S/49E-8ddb 140 3.68x10-3 4.6 118.6 -3.34 0.35 6.69 32.46 -0.17  -1.15 0.52 0.16 
17S/49E-35ddd 141 4.43x10-3 -0.9 158.3 -2.82 -0.09 6.68 31.02 -0.15  -1.38 0.19 -0.36 
Fortymile WashEast 
15S/49E-22a1 142 4.27x10-3 0.0 145.5 -2.83 0.17 5.44 23.00 -0.38 -1.12 -1.87 -0.46 -0.31 
15S/49E-22dcc 143 4.41x10-3 1.2 207.6 -1.50 -1.05 4.64 13.63 -0.41 -1.40 -3.20 -1.88 -2.84 
15S/49E-27acc 144 4.26x10-3 -1.3 153.3 -2.50 0.14 1.93 1.05 -0.94 -1.73 -2.94 -2.04 -0.37 
O'Neill Domestic 145 4.56x10-3 2.2 143.4 -2.79 -0.05 6.84 30.57 -0.21 -1.50 -1.72 -0.07 -0.85 
16S/49E-9cda 146 5.43x10-3 2.6 149.9 -2.46 -0.22 6.15 26.24 -0.24  -1.96 -0.38 -1.06 
16S/49E-9dcc 147 5.16x10-3 0.5 139.2 -3.08 0.22 6.57 31.04 -0.20  -1.25 0.32 -0.16 
16S/49E-16ccc 148 4.62x10-3 0.6 133.8 -2.79 0.06 6.32 28.15 -0.19  -1.64 -0.26 -0.73 
Ponderosa Dairy #1 149 6.29x10-3 -1.2 153.1 -2.33 -0.29 5.72 24.50 -0.23 -1.24 -1.91 -0.34 -1.02 
17S/49E-9aa 150 5.10x10-3 0.0 131.5 -2.90 0.06 6.25 28.64 -0.23  -1.54 0.11 -0.38 
17S/49E-15bbd 151 3.85x10-3 -0.7 119.6 -3.05 0.04 6.65 30.72 -0.19  -1.58 0.21 -0.34 
M. Gilgan Well 152 3.82x10-3 1.8 127.0 -3.11 0.15 6.49 30.56 -0.19 -1.08 -1.33 0.28 -0.27 
17S/49E-15bc 153             
Gravity Fault 
NC-EWDP-5S 154             
NC-EWDP-5SB 155 6.60x10-3 -0.2 221.3 -2.29 -0.42 4.59 14.45 -0.73 -1.50 -2.63 -1.46 -1.42 
16S/50E-7bcd 156 1.13x10-2 1.4 303.4 -2.12 0.27 4.19 14.45 -0.65  -2.37 -1.03 0.51 
Nelson Domestic 157 1.12x10-2 -3.8 325.0 -2.00 0.14 4.12 13.15 -0.70 -0.20 -2.58 -1.27 0.23 
16S/49E-12ddd 158 1.14x10-2 1.6 301.5 -2.16 0.18 4.39 13.17 -0.76  -2.62 -1.72 0.27 
Lowe Domestic 159 1.07x10-2 -1.5 284.4 -2.32 0.16 6.38 26.74 -0.38 -0.90 -1.88 -0.47 -0.03 
16S/49E-15aaa 160 8.50x10-3 -1.3 201.8 -2.43 0.08 5.75 23.76 -0.39  -1.97 -0.53 -0.25 
MDL-NBS-HS-000011 REV 02 A-135 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
MINERAL SATURATION INDICES2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Gravity Fault (Continued) 
Anvil Ranch Irrigation 161 8.09x10-3 1.5 139.8 -2.81 0.15 6.88 31.83 -0.18 -1.06 -1.47 0.21 -0.33 
16S/49E-36aaa 162 1.25x10-2 3.8 321.1 -2.33 0.45 5.39 22.40 -0.49  -1.89 -0.37 0.88 
16S/49E-35baa 163 1.21x10-2 0.1 325.8 -1.95 0.04 5.36 20.36 -0.48  -2.30 -0.88 -0.05 
Payton Domestic 164 1.19x10-2 -0.8 304.0 -2.19 0.16 5.88 23.63 -0.47 0.01 -2.16 -0.59 0.17 
16S/49E-36aba 165 1.14x10-2 2.3 302.3 -2.26 0.27 5.51 22.89 -0.44  -1.92 -0.39 0.54 
16S/49E-35aaa 166 1.11x10-2 4.8 280.3 -2.29 0.24 5.29 21.29 -0.50  -2.01 -0.54 0.38 
Oettinger Well 167 1.14x10-2 -2.0 307.9 -2.06 0.12 5.28 20.55 -0.48 -0.20 -2.22 -0.72 0.09 
Amargosa Motel (b) 168 1.12x10-2 -1.1 298.8 -2.17 0.20 5.63 22.94 -0.42 -0.27 -2.05 -0.54 0.28 
17S/49E-11ba 169 1.00x10-2 1.2 209.6 -2.82 0.44 6.34 29.04 -0.33  -1.38 0.16 0.74 
Spring Meadows Well #8 170             
17S/50E-19aab 171 1.46x10-2 1.2 405.5 -3.08 0.35 6.95 33.70 -0.38  -0.67 0.82 0.99 
USFWS - Five Springs 
Well 172 8.94x10-3 4.9 261.4 -2.07 0.18 3.38 8.48 -0.80 -0.91 -2.93 -1.63 0.42 
Spring Meadows Well #10 173             
18S/49E-1aba 174 8.51x10-3 -0.8 253.0 -3.27 0.75 7.53 38.08 -0.16  -0.62 1.11 1.44 
18S/50E-6dac 175 8.45x10-3 3.1 227.2 -2.87 0.41 6.52 31.77 -0.17  -0.91 0.56 0.87 
18S/50E-7aa 176 1.06x10-2 1.7 258.0 -3.08 0.50 7.53 35.92 -0.30  -1.00 0.63 0.75 
Amargosa River/Fortymile Wash 
16S/48E-36dcc 177 1.04x10-2 0.4 336.8 -1.73 -0.09 5.88 24.31 -0.23  -2.02 -0.58 -0.57 
Crane Domestic 178 1.42x10-2 -0.5 504.9 -1.56 0.12 5.24 19.91 -0.42 -0.14 -2.25 -0.89 0.04 
27N/4E-27bbb 179 1.30x10-2 2.4 448.3 -2.21 0.61 6.70 31.22 -0.19  -1.27 0.26 1.05 
IMV on Windjammer 180 9.65x10-3 -0.8 321.2 -2.05 0.10 6.25 26.99 -0.23 -0.32 -1.75 -0.35 -0.12 
17S/49E-29acc 181 1.37x10-2 5.0 288.6 -2.21 0.15 6.75 30.78 -0.18  -1.39 0.10 0.05 
17S/49E-28bcd 182 9.34x10-3 1.8 307.7 -2.15 0.19 6.15 27.12 -0.22  -1.62 -0.20 0.10 

MDL-NBS-HS-000011 REV 02 A-136 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
MINERAL SATURATION INDICES2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Amargosa River/Fortymile Wash (Continued) 
18S/49E-2cbc 183 9.42x10-3 0.1 360.7 -2.28 0.28 6.11 26.86 -0.29  -1.49 -0.23 0.51 
Mom's Place 184 6.77x10-3 -0.5 241.7 -2.45 0.10 6.57 29.79 -0.18 -0.55 -1.47 -0.01 -0.08 
18S/49E-11bbb 185 8.40x10-3 4.5 234.5 -2.26 -0.01 6.28 28.08 -0.18  -1.53 -0.12 -0.28 
Skeleton Hills 
TW-5 186 1.10x10-2 -1.5 400.0 -2.30 0.54 3.77 12.02 -0.83 -0.41 -2.37 -1.12 1.19 
Unnamed Well 15S/50E- 
22-7 187 4.19x10-3 8.6 171.5 -1.62 -1.20 5.23 16.45 -0.38 -1.43 -3.18 -1.81 -3.18 
Amargosa Flat 
Amargosa Tracer Hole #2 188 8.57x10-3 -0.4 279.8 -2.54 0.64 3.94 13.13 -0.78 -0.77 -2.45 -1.11 1.32 
Cherry Patch Well, 
17S/52E-08cdb 189 2.37x10-2 2.5 307.4 -1.88 -0.02 4.48 14.33 -0.67 -0.77 -2.39 -1.52 0.01 
USDOE-MSH-C shallow 
Well 190 7.40x10-3 -0.7 263.9 -2.63 0.07 5.82 23.92 -0.50 -1.14 -1.93 -0.47 0.46 
Mine Mountain 
UE-17a 191 9.51x10-3 14.9 208.5 -2.31 0.03 3.34 5.62 -1.01 -1.42 -3.27 -2.38 0.30 
UE-1a 192 9.02x10-3 -3.7 432.9 -1.81 0.21 4.21 11.64 -0.79  -3.24 -1.66 0.48 
UE-1b 193 5.32x10-3 18.9 197.6 -2.13 -0.15 5.94 25.26 -0.18  -2.20 -0.35 -0.37 
UE-16f 194 2.66x10-2 -15.7 902.7 -2.98 0.31 1.82 -0.30 -1.51 -1.59 -2.25 -1.88 1.08 
UE-14b 195 4.87x10-3 2.2 113.0 -3.36 0.01 5.59 23.60 -0.44  -1.36 -0.73 -1.35 
Pluto 1 196 5.92x10-3 5.9 150.4 -2.84 0.32 5.90 25.75 -0.34  -1.89 -0.22 0.38 
Pluto 5 197 7.65x10-3 7.4 220.2 -2.59 0.49 5.95 25.27 -0.31  -2.07 -0.51 0.93 
USGS Test Well F (HTH) 198 7.90x10-3 9.4 252.6 -1.31 -0.11 0.35 -6.49 -0.79 -0.57 -3.24 -2.17 -0.19 
MDL-NBS-HS-000011 REV 02 A-137 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-3. Calculated Geochemical Parameters of Groundwater Samples Used in this Report (Continued) 
Mineral Saturation Indices2,3 
Well 
Figure. 
A6-5 
Sample 
Ionic 
Strength 
Charge 
Balance 
Error 
(%)1 
DIC as 
(mg/L 
HCO3
) 
log 
PCO2 
(atm) Calcite Smectite Ca-Clino. SiO2 (a) Fluorite Albite 
KFeldspar 
Dolomite 
Funeral Mountains 
Woodcamp Spring 199 4.17x10-3 3.7 139.1 -2.15 -0.84 6.45 25.84 -0.26 -2.73 -2.59 -0.61 -2.26 
Bond Gold Mining #13 200 2.44x10-2 -5.3 296.7 -1.86 0.30 3.09 5.38 -0.91 -1.53 -3.29 -2.13 0.74 
Nevares Spring 201 1.27x10-2 -2.1 375.7 -1.78 0.20 2.87 6.81 -0.77 -0.49 -2.59 -1.53 0.53 
Travertine Spring 202 1.19x10-2 -2.3 366.1 -1.82 0.04 3.55 10.70 -0.67 -0.41 -2.45 -1.30 0.25 
DTN: LA0310EK831232.001 [DIRS 165995]. 
1 PHREEQC calculates percent error in the selected output file as 100 x (cations - |anions|)/(cations + |anions|), where cations is the electrical charge of the 
cations in equivalents per liter and anions is the electrical charge of the anions in equivalents per liter (Parkhurst and Appelo 1999 [DIRS 159511], p. 140). 
2 The saturation index of a mineral phase is calculated as the base-ten logarithm of the ratio of the ion activity product (IAP) to the solubility constant (Ksp) of the 
mineral at the prevailing temperature: log (IAP/Ksp). Values of log (IAP/Ksp) less than zero indicate the groundwater is undersaturated with that mineral. 
Conversely, values of log (IAP/Ksp) greater than zero indicate the groundwater is oversaturated with that mineral. Values of log (IAP/Ksp) equal to zero indicate 
the groundwater is at equilibrium with the mineral (Langmuir 1997 [DIRS 100051], p. 8). 
3 The log PCO2 and saturation indices for calcite, SiO2(a), fluorite, albite and K-feldspar were calculated using the database phreeqc.dat (Parkhurst and Appelo 
1999 [DIRS 159511], Table 55). The saturation indices for smectite and Ca-clinoptilolite were calculated based on the Gibbs free-energy data listed in 
Table A6-4 of this report. 
Table A6-4. Yucca Mountain Mineral Phase Compositions and Thermodynamic Data Used in PHREEQC Analyses 
Phase Formula 
.GO
f 
(kJ/mol-K) 
.HO
f 
(kJ/mol) Reference 
Smectite K0.1Na0.02Ca0.14Al4.4Si7.6O20(OH)44H2O -11,619.6 -12,595.6 Chipera et al. (1995 
[DIRS 100025], Table 1) 
Ca- 
Clinoptilolite K2.5Na1.1Ca1.2Al6.0Si30.0O72.026.8 H2O -39,067.7 -42,491.3 Chipera and Bish (1997 
[DIRS 105079], Tables 12) 
Na- 
Clinoptilolite K2.8Na1.5Ca0.9Al6.1Si29.9O72.026.8 H2O -39,093.8 -42,512.1 Chipera and Bish (1997 
[DIRS 105079], Tables 12) 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-138 November 2004 
The geochemical parameters calculated in this section provide an indication of which minerals 
are potentially dissolving or precipitating in Yucca Mountain groundwater and, thus, provide 
important constraints on groundwater mixing and reaction models. Table A6-3 indicates that 
groundwater in the Yucca Mountain area is generally slightly undersaturated with amorphous 
silica [SiO2(a)], fluorite, and albite and greatly supersaturated with Ca-clinoptilolite and smectite 
typical of Yucca Mountain. The spatial distribution of saturation indices of minerals whose 
saturation state in groundwater are more variable are discussed in more detail in the following 
subsections. 
In addition to the saturation indices shown in Table A6-3, saturation indices were also calculated 
for other common minerals (DTN: LA0310EK831232.001 [DIRS 165995). The calculated 
Na-clinoptilolite saturation indices generally are similar to those shown in Table A6-3 for 
Ca-clinoptilolite. All groundwaters in the Yucca Mountain area are significantly undersaturated 
with gypsum and halite and slightly oversaturated with quartz (chalcedony). Yucca Mountain 
area groundwaters are generally undersaturated with respect to sepiolite 
(Mg2Si3O7.5(OH)3H2O), except in areas of the Amargosa Desert such as the Gravity fault area 
where Si-rich groundwater from the volcanic alluvium mixes with Mg-rich discharge from the 
carbonate aquifer. Kaolinite saturation indices are zero in all cases because of the assumption 
(Table A5-1, Assumption 2) that all groundwaters are in equilibrium with kaolinite. 
A6.3.5.1 Ionic Strength 
Ionic strength (I) is a measure of the interionic effects resulting from the electrical attraction and 
repulsion between various ions in solution. It is defined by I = 1/2 2 
i i iZ C . (Langmuir 1997 
[DIRS 100051], p. 123), where Ci is the concentration (mol/kg solution) and Zi is the charge of 
ion i. Ionic strength is expressed in this report as moles per kilogram of groundwater. 
DTNs: GS980908312322.008 [DIRS 145412, GS990808312322.002 [DIRS 162917], GS010308312322.002, 
[DIRS 162910] GS011108312322.006 [DIRS 162911]. 
NOTE: The single large calculated Al value is from a sample with very small SiO2 value (UE-16f, sample 194). 
Figure A6-33. Comparison between Measured Dissolved Aluminum Concentrations and Dissolved 
Aluminum Concentrations Calculated by PHREEQC Assuming Equilibrium with Kaolinite 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-139 November 2004 
Excluding groundwater from the carbonate aquifer at borehole p#1, groundwater at Yucca 
Mountain has an ionic strength that ranges from about 2.2 x 103 to 4.8 x 103 mole/kg 
(Figure A6-34). A single groundwater from the Yucca Crest area from borehole H-3 (Site 51) 
has a somewhat higher value (6.12 x 10-3 mole/kg). The ionic strength of groundwater at the 
NC-EWDP wells in southern Yucca Mountain and south of Crater Flat increases toward the 
west, reflecting the differences in the ionic strength of the groundwater to the north and west of 
these wells. North of Yucca Mountain, groundwater shows a westward increase in ionic strength 
from the northern Fortymile Wash area through Timber Mountain and toward Oasis Valley. The 
highest ionic strength groundwaters are associated with the southwestern Crater Flat, the 
Amargosa River, the Gravity fault area, and central Jackass Flats. 
DTN: LA0310EK831232.001 [DIRS 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-34. Areal Distribution of Ionic Strength in Groundwater 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-140 November 2004 
A6.3.5.2 Dissolved Inorganic Carbon 
Dissolved inorganic carbon (DIC) represents the total amount of carbon present in all dissolved 
carbon species, including H2CO3, HCO3
, and CO3
2. It is expressed in Table A6-6 and 
Figure A6-35 as the mg/L HCO3
 having the same number of moles of carbon per liter. 
Although alkalinity changes can result from groundwater interactions with noncarbonate rocks, 
the DIC of groundwater can change only if (1) the groundwater mixes with groundwater having 
different DIC concentrations, (2) the groundwater dissolves carbon-bearing minerals such as 
calcite or dolomite, (3) calcite is precipitated from the groundwater, or (4) the groundwater 
interacts with CO2(g) in the overlying unsaturated zone. The last process tends to be of limited 
importance due to the very low diffusion of CO2(g) in water. Hence, in the absence of mixing, 
downgradient increases in DIC are a good indicator of contact between groundwater and either 
calcite or dolomite. 
DTN: LA0310EK831232.001 [DIRS 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-35. Areal Distribution of Dissolved Inorganic Carbon in Groundwater 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-141 November 2004 
Groundwater in the northern part of Yucca Mountain has relatively low concentrations of DIC 
(Figure A6-35). Somewhat higher DIC concentrations are found near Solitario Canyon in some 
of the SCW and YM-CR wells. Groundwater DIC concentrations increase toward the south at 
Yucca Mountain. The groundwater in Beatty Wash directly north of Yucca Mountain at well 
ER-EC-07 (Site 24) has similarly low DIC concentrations as northern Yucca Mountain, as does 
groundwater at most of the FMW-N wells northeast and east of Yucca Mountain. Southward 
along Fortymile Wash, the DIC concentrations of groundwater in the FMW-S wells increases 
and then decreases slightly but are generally low compared to the higher values found in 
groundwater in the surrounding AR, AR/FMW, and GF area wells. Groundwater in several of 
the wells in the Amargosa Valley area (LW group) has DIC concentrations that are nearly as low 
as that found at well J-11 (Site 67) in Jackass Flats. Groundwater in western and southwestern 
Crater Flat has much higher DIC concentrations than groundwater in the eastern part of the 
Crater Flat area, reflecting the presence of carbonate rocks at Bare Mountain. 
A6.3.5.3 Dissolved Carbon-Dioxide Partial Pressure 
The logarithm of dissolved carbon-dioxide partial pressure [log PCO2 (atm)] is generally higher 
than expected due to equilibrium with the atmosphere (log PCO2 = 3.5 atm) because of the much 
higher carbon-dioxide partial pressures found in the soil zone through which the water 
recharging the groundwater has passed. Soil-zone log PCO2 values can be 2.0 atm or greater 
depending on climate and vegetation cover. Unsaturated-zone log PCO2 at Yucca Mountain 
under the present climate is about 3.0 atm (Yang et al. 1996 [DIRS 100194]; Thorstenson et al. 
1998 [DIRS 126827]). However, CO2(g) production rates in the soil zones depend on climate, 
which has changed over time and presently changes with elevation and latitude (Quade and 
Cerling 1990 [DIRS 100073]), so unsaturated zone log PCO2 values could have been higher under 
past wetter climates. Most Yucca Mountain area groundwaters have log PCO2 values that are 
higher than are found in the unsaturated zone at Yucca Mountain. 
In the absence of climate change, the tendency in groundwater is for log PCO2 values to decrease 
downgradient from the recharge area as hydrogen ions and dissolved CO2 react with the rock to 
form secondary minerals and HCO3
 (Drever 1988 [DIRS 118564]). However, as stated above, 
climate change and other conditions particular to the recharge area can complicate this simple 
model. 
At Yucca Mountain, groundwater in the Solitario Canyon and Yucca Crest area generally has 
lower log PCO2 values than groundwater further to the east at Yucca Mountain (Figure A6-36). 
Along Fortymile Wash, groundwater log PCO2 values show an overall southward decrease 
between the FMW-N and FMW-S area wells. Groundwater log PCO2 values for well J-11 
(Site 67) in Jackass Flats and at some LW area wells are also relatively low, whereas log PCO2 
values are relatively high at wells in southwest Crater Flat and AR and AR/FMW area wells. 
A6.3.5.4 Calcite Saturation Index 
In general, calcite saturation indices (SIcalcite) are expected to increase along a flow path as H+ 
ions and dissolved CO2 are converted to HCO3
 and CO3
2- during silicate weathering reactions or 
Ca2+ and HCO3
 are added to the groundwater from calcite dissolution. Downgradient decreases 
in SIcalcite could result from loss of Ca2+ through mineral precipitation or ion exchange. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-142 November 2004 
DTN: LA0310EK831232.001 [DIRS 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-36. Areal Distribution of Dissolved Carbon-Dioxide Partial Pressure in Groundwater 
Groundwater north and northwest of Yucca Mountain in the Timber Mountain and Oasis 
Valley/Northwest Amargosa areas is generally saturated or supersaturated with calcite 
(Figure A6-37). Groundwater throughout most of Yucca Mountain is undersaturated with 
calcite, with the most undersaturated groundwater present in northern Yucca Mountain. Along 
Fortymile Wash, groundwater shows a southward increase in SICalcite. Almost all groundwater in 
the Amargosa Desert south of U.S. Highway 95 is saturated or supersaturated with calcite. 
Groundwater in most of the Crater Flat area is saturated or supersaturated with calcite. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-143 November 2004 
DTN: LA0310EK831232.001 [DIRS: 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-37. Areal Distribution of Calcite Saturation Index in Groundwater 
A6.3.5.5 Smectite Saturation Index 
Except for a few samples in the Mine Mountain area, groundwater throughout the Yucca 
Mountain region is supersaturated with smectite (Figure A6-38). The degree of supersaturation 
increases southward from Yucca Mountain toward the Amargosa Desert. If groundwater from 
Yucca Mountain and Fortymile Wash flows southward toward the Amargosa Desert, the 
southward increase in smectite saturation indices suggests that silicate-weathering reactions are 
providing ions to the groundwater faster than they can be removed by smectite precipitation. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-144 November 2004 
DTN: A0310EK831232.001 [DIRS: 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-38. Areal Distribution of Smectite Saturation Index in Groundwater 
A6.3.5.6 Calcium Clinoptilolite Saturation Index 
Throughout most of the Yucca Mountain region, groundwater is also supersaturated with 
Ca-clinoptilolite (Figure A6-39). As is the case for smectite, the degree of supersaturation 
increases southward from the Yucca Mountain area toward the Amargosa Desert. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-145 November 2004 
DTN: LA0310EK831232.001 [DIRS 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-39. Areal Distribution of Calcium Clinoptilolite Saturation Index in Groundwater 
A6.3.5.7 Potassium Feldspar Saturation Index 
Except for some wells in the Oasis Valley area, the groundwater at most wells along or north of 
U.S. Highway 95 are undersaturated with K-feldspar (Figure A6-40). Conversely, south of the 
site model area, most groundwater along or adjacent to Fortymile Wash is saturated or slightly 
supersaturated with K-feldspar, reflecting the much higher K and dissolved SiO2 concentrations 
of groundwater in these areas. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-146 November 2004 
DTN: LA0310EK831232.001 [DIRS: 165995]. 
Source: Table A6-1. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. 
UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-40. Areal Distribution of K-Feldspar Saturation Index in Groundwater 
A6.3.5.8 Summary of Areal Distribution of Calculated Geochemical Parameters 
If groundwater is moving southward from Yucca Mountain and Fortymile Wash into the 
northern Amargosa Desert, the areal distributions of calculated geochemical parameters 
presented in Table A6-3 and shown in Figures A6-34 to A6-40, combined with the areal 
distribution plots shown in Section A6.3.4, provide some insight into the potential reactions 
affecting groundwater compositions. Groundwater in these areas has low and relatively constant 
Cl concentrations (6-8 mg/L) compared to surrounding areas, and so downgradient changes in 
composition and in saturation indices can be attributed to water/rock interaction rather then 
evaporation. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-147 November 2004 
Silicate weathering reactions are indicated by the overall increase in dissolved SiO2 near the 
southern boundary of the SZ site model (Figure A6-3.6) and increases in pH (Figure A6-3.1), 
HCO3
 (Figure A6-3.4), and SIcalcite (Figure A6-37). Weathering of primary silicate minerals like 
plagioclase or K-feldspar typically involves the consumption of H+ ions and dissolved CO2 and 
the production of cations, HCO3
, dissolved SiO2, and secondary minerals like kaolinite or 
smectite, consistent with these trends (Drever 1988 [DIRS 118564], p. 151; Langmuir 1997 
[DIRS 100051], p. 325). The overall southward increase in SIK-feldspar (Figure A6-40) and 
accompanying increase in SISmectite (Figure A6-38) and SICa-clinoptilolite (Figure A6-39) indicate that, 
if secondary minerals are precipitated, the primary silicate dissolution reactions may be faster 
than the precipitation rates for the secondary minerals. The extreme supersaturation of smectite 
and Ca-clinoptilolite may be indicating that these precipitation reactions are kinetically inhibited. 
The saturation indices of alumino-silicate minerals are based the apparent control of 
Al3+ concentrations by kaolinite (Figure A6-33). Kaolinite has been documented only in trace 
amounts in the Yucca Mountain area, unlike zeolites, which are prevalent throughout the 
saturated zone near Yucca Mountain (Vaniman et al. 1996 [DIRS 105946]). Although this 
assumption is somewhat empirical (see Table A5-1, Assumption 2), it is reasonable because 
reaction pathways represented on phase-stability diagrams typically represent kaolinite as an 
intermediate weathering product that is eventually replaced by more stable secondary phases 
(Drever 1988 [DIRS 118564], Figure 8-8, pp. 156 to 158; Langmuir 1997 [DIRS 100051], 
Figure 9.14). 
A6.3.6 Sources and Evolution of Groundwater beneath Yucca Mountain 
The following sections provide an analysis of the origin and evolution of groundwater at 
Yucca Mountain. Data on perched water from the unsaturated zone at Yucca Mountain are 
presented in Section A6.3.6.1. Perched water compositions are taken to approximate the 
composition of local recharge from Yucca Mountain itself. Perched water compositions and 
other groundwaters upgradient from Yucca Mountain are compared to groundwater presently 
beneath Yucca Mountain evaluate the possible sources of Yucca Mountain groundwaters. 
A6.3.6.1 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 that is more likely to represent 
in situ chemical and isotopic conditions for the following reasons. Drilling may affect the 
chemical and isotopic composition of water in the borehole by introducing foreign drilling fluids 
(generally air) into the water and by grinding the rock, thereby exposing fresh, unaltered rock 
surfaces that may react with the water. To minimize these drilling effects, a borehole is typically 
purged of water present in the borehole, and many additional borehole water volumes are 
pumped from the formation before sampling. This process increases confidence that the water 
sample represents actual hydrochemical conditions in the formation. In cases for which a water 
sample is bailed without first pumping the borehole, the water sample may not be representative 
of in situ hydrochemical conditions. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-148 November 2004 
Of the perched-water samples considered in this analysis, samples from boreholes SD-9 and 
NRG-7a (Table A6-5) were obtained exclusively by bailing (Yang and Peterman 1999 
[DIRS 149596], 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 A6-5) obtained prior to August 17, 1993, were 
obtained without first pumping the borehole. Pumped samples were obtained between August 17 
and August 27, and an additional bailed sample was taken after pumping on August 31, 1993. A 
time series of delta strontium-87 (d87Sr) versus water production showed that d87Sr values 
continued to change until about 12,000 liters had been pumped from the borehole, or sometime 
after August 25, 1993 (Yang and Peterman 1999 [DIRS 149596], Table 19, Figure 113). 
Therefore, the d87Sr data, and likely other data, obtained from samples collected from UZ-14 
after this date probably best represent in situ conditions. These samples include UZ-14 PT-4 and 
UZ-14 D (Table A6-5). 
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 [DIRS 100194], p. 37). 
Perched water was sampled by pumping from borehole WT-24. However, according to 
Patterson et al. (1998 [DIRS 107402], 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 a clean-out period. Only data collected from borehole WT-24 following this 
clean-out period are presented in this report. 
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 or 
after 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. 
MDL-NBS-HS-000011 REV 02 A-149 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-5. Chemical and Isotopic Composition of Perched Water at Yucca Mountain 10-5 
Chemical Concentrations (mg/L) 
Water 
Sample 
Depth 
(m) 
Sampling 
Method Date pH Ca2+ Mg2+ Na+ K+ Cl SO4
2 HCO3
 SiO2 13C() 14C(pmc) 
3Ha 
(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 197c 64.2 14.4 41.8 0 97.8 13.3  449 
SD-9 
 Bailed 09-12-94               2.42b 497 
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 
MDL-NBS-HS-000011 REV 02 A-150 November 2004 
Saturated Zone Site-Scale Flow Model 
Table A6-5. Chemical and Isotopic Composition of Perched Water at Yucca Mountain (Continued) 
Chemical Concentrations (mg/L) 
Water 
Sample 
Depth 
(m) 
Sampling 
Method Date pH Ca2+ Mg2+ Na+ K+ Cl SO4
2 HCO3
 SiO2 13C() 14C(pmc) 
3Ha 
(TU) 
dD 
() 
d18O 
() 
234U/238U 
Activity 
Ratio 
36Cl/Cl 
(x 1015) 
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 8.34 596 WT-24d  
Pumped 12-10-97 8.6 18.0 1.3 37.5 2.9 8.9 16.0 121.0 36.5 10.8 --- ---  
100.6 
-13.5 8.12 --- 
 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  491 
NRG-7a 
 Bailed 03-08-94                474 
DTNs: GS980108312322.005 [DIRS 149617] (ions, pH, d13C, dD, d18O, 3H)d, GS950808312322.001[DIRS 148114] (3H), GS010808312322.004 [DIRS 156007] 
(234U/238U activity ratios), GS951208312272.002 [DIRS 151649] (3H), LAJF831222AQ98.011[DIRS 145402] (36Cl/Cl), MO0007GNDWTRIS.013 
[DIRS 151504] (d13C, dD, d18O, 14C), MO0007MAJIONPH.016 [DIRS 151533] (ions and pH), GS980908312322.008 [DIRS 145412] (14C)d 
NOTES:  not available 
a Tritium analyses have an accuracy of plus or minus 12 TU. 
b These results are not representative of in situ conditions due to sample contamination. 
c This sample also contains 10 mg/L CO3
2. 
d Average values of samples collected on the indicated date. 

Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-151 November 2004 
A6.3.6.2 Evidence from 234U/238U Activity Ratios for Local Recharge 
Precipitation typically contains low concentrations of solutes, including uranium. As the 
precipitation infiltrates through the soil, uranium is dissolved from the readily soluble soil 
components. Measured 234U/238U activity ratios in secondary minerals formed in soil zones on 
Yucca Mountain range from 1.4 to 1.8 reflecting both enrichment and dissolution processes 
(DTNs: GS010608315215.002 [DIRS 156187], GS970808315215.012 [DIRS 145921], and 
GS980908312322.009 [DIRS 118977]). Pore waters extracted from a small number of core 
samples from the unsaturated zone at Yucca Mountain have 234U/238U activity ratios that range 
from 1.5 to 3.8. 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 stratigraphically lower upper lithophysal unit of the welded Topopah Spring tuff (Tpt) have 
234U/238U activity ratios of 2.5 to 3.8 (DTN: MO0012URANISOT.000 [DIRS 153384], 
pp. 1 to 4). These data, as well as data from fracture-lining minerals (Paces et al. 1998 
[DIRS 107408], Figure 3), suggest a general increase in 234U/238U activity ratios in pore waters 
from the soil zone down through the upper unsaturated zone. 
Activity ratios of 234U/238U in perched-water samples range from 3.5 at borehole SD-7 to 8.4 at 
borehole WT-24 (DTNs: GS010608315215.002 [DIRS 156187] and GS010808312322.004 
[DIRS 156007]). The values at the high end of this range are unusual and suggest the existence 
of certain flow conditions. In particular, the high ratios require that the 234U enrichment 
processes discussed in Section A6.3.1.2.4 dominate over dissolution of uranium-bearing 
minerals. This situation suggests small water-to-rock ratios. For the unsaturated zone at Yucca 
Mountain, the high 234U/238U ratios are consistent with small water fluxes passing through a 
fracture network. In fractures with small, and probably intermittent water fluxes, 234U will 
accumulate over time whereas the relative amount of 238U that may be incorporated into the 
water via dissolution will likely be small. In this way, a small flux of water flowing through a 
fracture may preferentially incorporate 234U relative to 238U, resulting in water with an elevated 
234U/238U ratio, as suggested by Paces et al (2001 [DIRS 156507] and 2002 [DIRS 158817]). 
The progressive 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 depend on the 238U content of the host rock, the weathering 
characteristics of the rock, the water volume to rock surface area, redox conditions, and other 
factors (Clark and Fritz 1997 [DIRS 105738], pp. 238 to 240). The 234U/238U activity ratio of the 
perched water may either increase or decrease with time, depending on the relative importance of 
these factors. 
The elevated 234U/238U activity ratios found in Yucca Mountain perched water and shallow 
groundwater are attributable to unsaturated zone flow through the thick sequence of fractured, 
welded tuffs that constitute the Topopah Spring tuff. Figure A6-41 summarizes the change in 
234U/238U ratios with depth in the vicinity of Yucca Mountain. In surface water and pore water 
from the nonwelded PTn, 234U/238U activity ratios are small, reflecting the relatively important 
contribution of 238U from dissolution. Deeper in the subsurface, calcite and opal from the ESF 
have higher, though variable 234U/238U activity ratios. The variability of these ratios is attributed 
to precipitation of these materials from waters that have experienced variable transport times and 
paths through the unsaturated zone (Paces et al. 2001 [DIRS 156507], p. 63). Permeable vitric 
tuffs are absent beneath the Topopah Spring tuff in the northern part of Yucca Mountain 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-152 November 2004 
(Rousseau et al. 1999 [DIRS 102097], Figure 16) where perched water has high 234U/238U. In 
this part of the mountain, recharge to the saturated zone is estimated to occur mainly along faults 
and other preferential pathways due to the low permeability of the underlying zeolitic tuffs 
(BSC 2004 [DIRS 169861], Appendix A and Figure 6.6-3 ). Toward the southern part of the 
central block, however, thick permeable vitric intervals activity ratios and uranium in perched 
water at boreholes UZ-14 and WT-24 in northern Yucca Mountain, where vitric tuffs are thin or 
absent. The relatively low 234U/238U activity ratio (3.5) and higher uranium concentrations for 
perched water at borehole SD-7 compared to perched water in boreholes WT-24 and UZ-14 
(Paces et al 2002 [DIRS 158817], Table 2) are consistent with this conceptual model. 
Source: Modified from Paces et al 2001 [DIRS 156507], Figure 37. 
Figure A6-41. Uranium Isotopic Compositions and Schematic Evolutionary Trends at Yucca Mountain 
In summary, the high 234U/238U activity ratios found in some Yucca Mountain perched water are 
interpreted to be due to percolation of groundwater through a very thick unsaturated interval of 
fractured, welded tuff. In the northern part of Yucca Mountain where deep, permeable vitric 
tuffs are absent and recharge occurs by preferential flow along faults, the relatively 
high 234U/238U activities are unmodified by further bulk-rock dissolution. In the southern part of 
Yucca Mountain where deep unsaturated flow takes place through the matrix of vitric, 
nonwelded tuffs, bulk-rock dissolution may reduce the high 234U/238U activity ratios acquired by 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-153 November 2004 
fracture flow through the welded tuffs. One inference of this conceptual model is that the high 
234U/238U activity ratios found in groundwater near Dune Wash at boreholes WT-3, WT-12, and 
WT-17 may reflect recharge through areas where deep vitric tuffs are absent, such as north of the 
Drill Hole Wash area (the reader should note that in this appendix the location WT-3 refers to 
UE-25 WT #3 and WT-12 refers to UE-25 WT #12). However, the necessary data from the deep 
unsaturated zone are too few to fully substantiate this hypothesis at this time. 
A6.3.6.3 Evidence for Local Recharge from Other Chemical Constituents 
This section compares other chemical and isotopic characteristics of perched water and 
groundwater to further evaluate that Yucca Mountain recharge, as represented by perched water, 
is the principal source of groundwater beneath Yucca Mountain. A comparison of perched water 
analyses from Table A6-5 with SZ groundwater from Yucca Mountain (YM-CR, YM-C, YM-SE 
and YM-S groups) and groundwater upgradient from Yucca Mountain in the TM, FMW-N, 
SCW, and CF groups are shown in Figures A6-42 to A6-46. 
The scatter plot of SO4
2 versus Cl (Figure A6-42) shows that perched waters pumped from 
boreholes UZ-14, WT-24, and SD-7 have SO4
2 and Cl concentrations that are similar to those 
of groundwaters at many YM-CR area wells. These concentrations plot near a line, termed the 
Southern Nevada Precipitation line that was derived by considering how the SO4
2 and 
Cl-concentrations measured in precipitation from the Kawich Range, just north of the Nevada 
Test Site, would change with progressive evaporation. With progressive evaporation, the 
dissolved SO4
2 and Cl concentrations in the remaining water would increase and plot along a 
line with a slope (2.7) equal to the ratio of their concentrations in precipitation (96 and 35 mg/L, 
respectively) (Meijer 2002 [DIRS 158813], Table 1). Groundwaters that plot on or near the 
Southern Nevada Precipitation line are likely to have had most of their SO4
2 and Cl derived 
from atmospheric deposition of salts composed of these ions. 
In contrast, other Yucca Mountain groundwaters, particularly groundwaters at some YM-S sites, 
show elevated SO4
2 concentrations relative to perched water and appear to trend from the 
perched-water data toward the p#1 mixing line. This line (slope = 5.7) is defined by the origin 
and groundwater SO4
2 and Cl concentrations from the carbonate aquifer at borehole p#1 
(160 and 28 mg/L, respectively). Groundwaters that included a component of groundwater from 
the carbonate aquifer would be expected to trend toward this line, depending on the 
concentrations of SO4
2 and Cl dissolved in the groundwater before mixing occurred. Elevated 
groundwater SO4
2 concentrations relative to the Southern Nevada Precipitation line could also 
indicate the addition of SO4
2 through the dissolution of S-bearing minerals like gypsum, pyrite 
or alunite. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-154 November 2004 
Source: Tables A6-1 and A6-5. 
NOTES: Sample p#1 plots well above limits of the figure. This figure has color-coded data points and should not be 
read in a black and white version. Perched water data are represented by open symbols. The more 
representative samples of perched water from borehole UZ-14 are labeled in the figure. 
Figure A6-42. Scatter Plot Comparing Sulfate and Chloride Compositions of Perched Waters and 
Saturated Zone Groundwaters 
The scatter plot of d13C versus 1/DIC (Figure A6-43) shows that perched water at 
Yucca Mountain is generally more dilute in DIC and has lighter d13C than most Yucca Mountain 
groundwater, although some groundwater from the YM-CR group in northern Yucca Mountain 
has comparable DIC and d13C values. No systematic differences between the northern 
(boreholes UZ-14 and WT-24) and central Yucca Mountain perched water (borehole SD-7) 
compositions are evident in d13C and DIC compositions, suggesting the relative uniformity of 
recharge compositions throughout Yucca Mountain. The Yucca Mountain groundwater shows 
an overall southward trend toward heavier d13C and higher DIC concentrations (lower 1/DIC). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-155 November 2004 
Source: Tables A6-2, A6-3, and A6-5. 
NOTES: This figure has color-coded data points and should not be read in a black and white version. Perched 
water data are represented by open symbols. The more representative samples of perched water from 
borehole UZ-14 are labeled in the figure. 
Figure A6-43. Scatter Plot Comparing Delta Carbon-13 and Dissolved Inorganic Carbon Compositions of 
Perched Waters and Saturated Zone Groundwaters 
Perched groundwater at Yucca Mountain has d18O and dD compositions that are slightly heavier 
in dD but generally similar to many YM-CR groundwaters (Figure A6-44). Elsewhere at Yucca 
Mountain, groundwaters tend to be lighter in dD than the perched water. There is an overall 
southward trend toward lighter dD among the YM-CR, YM-C, YM-SE and YM-S groups. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-156 November 2004 
Source: Tables A6-2 and A6-5. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. The solid lines 
are the global meteoric water line (dD = 8 d18O + 10) (Clark and Fritz 1997 [DIRS 105738], p. 36) and a 
possible paleometeoric water line for southern Nevada (dD = 8 d18O + 5) (White and Chuma 1987 
[DIRS 108871], pp. 573 to 574). Perched water data are represented by open symbols. The more 
representative samples of perched water from borehole UZ-14 are labeled in the figure. 
Figure A6-44. Scatter Plot Comparing Delta Deuterium and Delta Oxygen-18 Data for Perched Water 
and Groundwater near Yucca Mountain 
Perched waters at Yucca Mountain have 14C activities that are higher than most Yucca Mountain 
area groundwaters (Figure A6-45). As discussed in connection with Figure A6-43, the 
d13C values of perched water are comparable to or lighter than all but a few of the Yucca 
Mountain area groundwaters. These groundwaters show a southward trend toward heavier d13C 
and lower 14C activities. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-157 November 2004 
Source: Tables A6-2 and A6-5. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. Perched water 
data are represented by open symbols. The more representative samples of perched water from borehole 
UZ-14 are labeled in the figure. 
Figure A6-45. 14C Activity versus Delta 13C of Perched Water and Groundwater near Yucca Mountain 
Perched waters at Yucca Mountain have higher Ca2+ and lower Na+ concentrations than most 
Yucca Mountain groundwaters (Figure A6-46). The YM-C and YM-SE area groundwaters are 
most similar to the perched water with regard to Ca2+ and Na+ concentrations, whereas most 
YM-CR and YM-S groundwater have substantially less Ca2+ and more Na+ than the perched 
water. Some YM-S groundwaters and one YM-C groundwater (from well H-4) also appear to be 
affected by mixing with carbonate aquifer groundwater like that found at borehole p#1, indicated 
by increased Ca2+ and Na+ concentrations in these groundwaters along a mixing trend defined by 
the groundwaters from well p#1. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-158 November 2004 
Source: Tables A6-1 and A6-5. 
NOTE: This figure has color-coded data points and should not be read in a black and white version. Perched water 
data are represented by open symbols. The more representative samples of perched water from borehole 
UZ-14 are labeled in the figure. 
Figure A6-46. Scatter Plot Comparing Calcium and Sodium Compositions of Perched Waters and 
Saturated Zone Groundwaters 
In summary, groundwater chemical and isotopic compositions at Yucca Mountain are compatible 
with the hypothesis that much or most of the groundwater is derived from local recharge. The 
perched-water and groundwater Cl and SO4
2 concentrations are similar, although southward 
increases in groundwater SO4
2 concentrations require some additional sources of SO4
2 through 
water-rock interaction or mixing with groundwater having higher SO4
2 concentrations. 
Similarly, the d13C and DIC concentrations of perched water are similar to those of groundwater 
in northern Yucca Mountain, but water-rock interactions involving isotopically heavy calcite or 
mixing with small amounts of a groundwater having high DIC concentrations and heavy d13C is 
required to explain the southward increases in d13C and DIC. Perched water d18O and dD 
compositions are similar to those found in groundwater in northern Yucca Mountain but are 
slightly heavier than those found toward the southern end of the mountain. Because climate 
change has probably affected the d18O and dD composition of recharge over time (see 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-159 November 2004 
Section A6.3.1.2), the differences between the perched water d18O and dD compositions and 
groundwater d18O and dD compositions elsewhere at Yucca Mountain do not rule out local 
recharge as a source for these groundwaters. The higher 14C activities of the perched water 
compared to Yucca Mountain groundwater are compatible with the hypotheses that 
Yucca Mountain groundwater is derived from local recharge. Groundwater is expected to be 
older than the recharge from which it is derived. Similarly, the fact that perched water has high 
Ca2+ and lower Na+ than the underlying groundwater is compatible with local recharge being the 
source of the groundwater. Pore-water analyses from the deep unsaturated zone indicate that 
Ca2+ is exchanged for Na+ on minerals in the deep unsaturated zone (Meijer 2002 
[DIRS 158813], p. 799), consistent with the observed relation between Ca2+ and Na+ in the 
perched and SZ waters. Likewise, it appears that other divalent cations like Mg2+ and Sr2+, as 
well as Ca2+, are selectively removed by zeolites in exchange for Na+ (and perhaps for K+) in the 
deep unsaturated zone (Vaniman et al. 2001 [DIRS 157427], Table 2). 
A6.3.6.4 Evaluation of Saturated Zone Flow beneath Yucca Mountain 
The steep gradient in the potentiometric surface to the north and along the west side of Yucca 
Mountain requires flow in southerly or easterly directions beneath Yucca Mountain. The N-S 
and NW-SE fault orientations in the area may also focus flow in these directions. Therefore, if 
SZ groundwater does contribute to flow beneath Yucca Mountain, then this groundwater would 
most likely originate from the north, northwest or west. These possibilities are evaluated below. 
For the most part, the hydrochemistry of groundwater north of Yucca Mountain that was 
sampled as part of the NTS Underground Test Area Restoration Project 
(DTN: LA0311EK831232.001 [DIRS 166068]) differs from that of SZ groundwater beneath 
Yucca Mountain. As shown in Figures A6-32, A6-33, and A6-42, the Cl and SO4
2 
concentrations of most samples in the Timber Mountain group are substantially higher than those 
for Yucca Mountain groundwater. Similarly, d13C are generally too heavy and the 14C too low 
for groundwater near Timber Mountain to be the primary source of Yucca Mountain 
groundwater (Figure A6-45). Only one well (ER-EC-07, Sample 24) in Beatty Wash has Cl, 
SO4
2, d13C, and 14C values that suggest it could be a major component of the groundwater 
beneath Yucca Mountain (Figures A6-42 and A6-45). Although limited data for d87Sr are 
available from Yucca Mountain, the d87Sr in groundwater from the northernmost well at Yucca 
Mountain (G-2) is too high for this groundwater to have originated from groundwater at well 
ER-EC-07 (Figure A6-49). The much higher Sr2+ concentrations in groundwater at well 
ER-EC-07 compared to all northern Yucca Mountain groundwater (Figure A6-48) indicates that 
acquisition of more radiogenic strontium through water-rock interaction during flow between 
wells ER-EC-07 and G-2 is not a likely explanation for the difference in d87Sr values at these 
wells. 
It has been suggested that water may upwell from the carbonate aquifer into the tuff aquifer of 
Yucca Mountain (Stuckless et al. 1991 [DIRS 101159]). The Cl and SO4
2 concentrations in 
groundwater from borehole p#1(c) are substantially elevated over those of the tuff aquifer, as 
discussed above. The Cl and SO4
2 concentrations of groundwater at borehole p#1 are similar to 
those of groundwater from other areas where carbonate rocks are present (e.g., Crater FlatSW), 
suggesting that groundwater from borehole p#1 may be representative of compositions in the 
carbonate aquifer beneath Yucca Mountain. Groundwater from sample p#1(c) also has much 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-160 November 2004 
higher d13C, lower 14C, and much higher concentrations of DIC, Ca2+, and Na+ 
(Figures A6-43 A6-46) when compared to the tuff aquifer. As is evident from Figures A6-42 to 
A6-46, most of the groundwater samples from the volcanic aquifer do not resemble the 
groundwater sampled at p#1(c). These data clearly indicate that groundwater from the carbonate 
aquifer does not constitute a major part of the groundwater beneath Yucca Mountain. However, 
the higher Cl and SO4
2 concentration as well as other constituents (Figure A6-46) of sample 
p#1(v) are readily 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 [DIRS 101040], p. 49). 
Carbon isotope data can be used to limit the amount of mixing of waters in the volcanic and 
Paleozoic aquifers, as follows. The d13C and DIC of the carbonate aquifer at p#1(c) are 2.3 per 
mil (Table A6-2) and 976.6 mg/L as HCO3
 (Table A6-3), respectively. In contrast, for 
groundwater samples where uranium isotopes indicate only Yucca Mountain recharge exists 
(i.e., samples 43, 44, 60, 64, 65, and 66) the average DIC concentration is about 
143.6  18.6 mg/L as HCO3
 and the average d13C is 9.11.4 per mil (Note: uncertainty is 
given as 1 standard deviation and the d13C of sample 59 was used for sample 60). Mixing 
calculations were done using the composition for sample p#1(c) and the average composition of 
Yucca Mountain recharge from samples 43, 44, 60, 64, 65, and 66 as end members. The 
calculations employed the relations DICmix = XcDICc + (1-Xc)DICv and d13CmixDICmix = 
Xcd13CcDICc + (1-Xc)d13CvDICv, where Xc is the fraction of groundwater from the carbonate 
aquifer in the mixture and the subscripts mix, c, and v indicate that the variables pertain to the 
mixture, carbonate aquifer, and volcanic aquifer, respectively. These calculations indicate that 
the presence of 10 percent carbonate aquifer water would increase the DIC and d13C of Yucca 
Mountain recharge water to 227 and 6.2 per mil, respectively; similarly, the presence of 
20 percent carbonate aquifer water in the mixture would increase DIC and d13C to 310 and 
-4.8 per mil, respectively. On the basis of these calculations, groundwater from borehole USW 
H-3 (Site 51) with a DIC concentration of 240.9 mg/L HCO3 and a d13C of 4.9 per mil may 
have approximately 10 to 20 percent carbonate aquifer water. However, all other samples from 
the Yucca Mountain block have less than 5 percent carbonate aquifer water. These relatively 
small amounts of carbonate aquifer water in the volcanic aquifer probably form upper limits 
because isotopically heavy calcite is present in the volcanic aquifer that, if dissolved, would 
result in effects on DIC and d13C compositions similar to those produced by mixing. 
Groundwater from the Solitario Canyon Wash (SCW) area wells is similar with respect to most 
chemical and isotopic constituents to groundwater in the southern Yucca Mountain (YM-S) well 
grouping and to groundwater from wells H-3 (Site 51) and SD-6 (Site 50) in the Yucca Crest 
(YM-CR) grouping (Figures A6-42 to A6-46). The chemical and isotopic similarities between 
the SCW and YM-S groupings indicates the generally southward flow of groundwater from the 
SCW area wells, whereas the chemical and isotopic similarities between groundwaters at wells 
H-3 and SD-6 and SCW area groundwater is compatible with at least a small amount of 
groundwater leakage eastward across the Solitario Canyon fault. However, because the vast 
majority of YM-C and YM-SE area groundwaters appear to be unrelated to groundwater from 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-161 November 2004 
the Solitario Canyon area, groundwater leakage from Solitario Canyon to these areas must be 
relatively small compared to other groundwater sources, such as local recharge. 
In summary, considerable hydrochemical evidence exists to support the hypothesis that the bulk 
of the SZ water beneath Yucca Mountain was derived from local recharge. Similarly, evidence 
in support of groundwater flow to Yucca Mountain from upgradient areas is weak. Exceptions to 
this are leakage of groundwater from the Solitario Canyon area into groundwater at wells SD-6 
and H-3, and potentially wells in southern Yucca Mountain, including those near Fortymile 
Wash. Local upwelling of relatively small amounts (generally less than 5 percent) of carbonate 
aquifer water into the volcanic aquifer is permitted by the groundwater data from most YM-CR, 
YM-C and YM-SE area wells. 
On the basis of the above discussions, groundwater beneath Yucca Mountain is best 
characterized by generally low concentrations of dissolved solids and by high 234U/238U activity 
ratios. Lower 234U/238U ratios do not, however, exclude the presence of Yucca Mountain 
recharge in the groundwater. Low 234U/238U activity ratios (less than 6) in downgradient 
groundwater can result from recharge in southern Yucca Mountain with a lower 234U/238U 
activity ratio, mixing of Yucca Mountain recharge with groundwater from other sources, and 
water-rock interactions that add dissolved uranium to the groundwater. 
A6.3.6.5 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. In particular, the chloride 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 A6-47). 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 (e.g., Dettinger 1989 [DIRS 105384], p. 59) uses the following equation to 
calculate the infiltration rate (I, in mm) when runoff or run-on is negligible: 
I = (P C0)/Cp (Eq. A6-7) 
where 
P is average annual precipitation (mm) 
C0 is average Cl concentration in precipitation, including the contribution from dry fallout 
(mg/L) 
Cp is the measured Cl concentration in groundwaters (mg/L). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-162 November 2004 
The CMB method (Figure A6-47) assumes steady one-dimensional, downward piston flow, 
constant average annual precipitation rate, constant average annual Cl deposition rate (PC0), 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 (Table A5-1, Assumption 5). When these conditions are 
met, the estimates of infiltration rate are equal to the recharge rate at the water table; the terms 
infiltration rate and recharge rate are used interchangeably in the remainder of this section. 
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 [DIRS 105384], p. 75). Using a 6-year study of two upland basins selected as 
analogue wetter climate sites for Yucca Mountain, Lichty and McKinley (1995 [DIRS 100589], 
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. 
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 scientific analysis report (BSC 2001 [DIRS 160247], 
Section A6.9.2.2). Values of net infiltration estimated at Yucca Mountain using the CMB 
method range from less than 0.5 mm/year in washes to a maximum of nearly 20 mm/year 
beneath ridgetops and side slopes (based on data and calculations in 
DTNs: (LA0002JF831222.001, [DIRS 147077] LA0002JF831222.002 [DIRS 147079], 
LA9909JF831222.010 [DIRS 122733], LA9909JF831222.012 [DIRS 122736]; and BSC 2001 
[DIRS 160247], Section A6.9.2.4), depending on the Cl deposition rate assumed in the 
calculation. 
Table A6-6 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 [DIRS 116809], p. 677), and estimates of average Cl concentrations in precipitation at 
Yucca Mountain range from 0.3 to 0.6 mg/L (BSC 2001 [DIRS 160247], Section A6.9.2.3). To 
bound the recharge rate estimates, Rate 1 in Table A6-6 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/year for Rate 1 and 14  2 mm/year for Rate 2 (Table A6-6). 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 SZ 
samples, as well as to mixing in the aquifer and in the borehole when the SZ samples were 
pumped. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-163 November 2004 
For illustration only. 
NOTES: Part (a) illustrates the underlying basis of the CMB method. Part (b) shows pore-water Cl concentrations 
as a function of infiltration, assuming a range of chloride deposition rates (106 to 183 mg pore-water 
Cl- /(m-2 year). Using an average annual precipitation rate of 170 mm (Hevesi et al. 1992 [DIRS 116809], 
p. 677), these deposition rates correspond to effective Cl concentrations of 0.62 mg/L to 1.07 mg/L in local 
precipitation. 
Figure A6-47. Chloride Mass-Balance Method for Estimating Infiltration 
As indicated in the following section, it appears from interpretations of both stable isotope 
(dD and d18O) and 14C data that most of the groundwater presently beneath Yucca Mountain 
infiltrated in the late Pleistocene, when precipitation and Cl deposition rates were potentially 
different from present conditions. It is estimated from wood rat midden data that mean annual 
precipitation during the Pleistocene was 1.9 times present precipitation at a 1,500-m elevation 
and 1.3 times present precipitation at a 750-m elevation (Forester et al. 1999 [DIRS 109425], 
p. 32). For the elevation range of 1,000 to 1,500-m that encompasses the surface elevations of 
most wells listed in Table A6-6 (DTN: GS010908312332.002 [DIRS 163555]), an average 
increase in Pleistocene precipitation of 1.7 times present precipitation can be estimated for Yucca 
Mountain. However, it is not clear if Cl concentrations in precipitation were the same during 
the Pleistocene or if Cl concentrations decreased so that Cl deposition rates (the product of 
P and C0) were constant or even lower than today. If Cl concentrations in precipitation were 
similar in the late Pleistocene to those of the present day, Pleistocene infiltration rates may have 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-164 November 2004 
been approximately 70 percent higher, on average, than the rates listed in Table A6-6 using 
present-day precipitation rates and Cl concentrations. On the other hand, if Cl deposition rates 
in the Pleistocene were approximately the same as today, as inferred by (Plummer et al. 1997 
[DIRS 107034], p. 540) from 36Cl/Cl ratios in packrat middens, the infiltration rates listed in 
Table A6-8 using present-day Cl deposition rates are valid. 
A6.3.6.6 Evaluation of Evidence for Timing of Recharge 
Hydrochemical data that bear on the question of the age or timing of local recharge include 
hydrogen and oxygen isotope ratios and 14C activities. Hydrogen and oxygen isotope ratios may 
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. 
Table A6-6. Recharge Rates Based on the Chloride Mass Balance Method 
Apparent Recharge Ratea (mm/year) 
Well Identifier 
Chloride 
concentration 
(mg/L) Rate 1 Rate 2 
G-2 6.5 7.8 15.7 
UZ-14 (sh) 6.9 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(95-97) 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 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-165 November 2004 
Table A6-6. Recharge Rates Based on the Chloride Mass Balance 
Method (Continued) 
Apparent Recharge Ratea (mm/year) 
Well Identifier 
Chloride 
concentration 
(mg/L) Rate 1 Rate 2 
WT-17 6.4 7.7 15.5 
WT#3 6.0 8.2 16.5 
Source: Table A6-1. 
a Infiltration rates were calculated based on equation (7). Rate 1 is calculated 
using the lower estimate for Cl concentration in precipitation (0.3 g/L); Rate 2 
is calculated using the higher estimate (0.6 mg/L). Recharge estimates 
obtained by the CMB method are based on Table A5-1, 
Assumption 5. 
b Approximately 28.6 percent of the water in this sample is from upward flow in 
the borehole from the carbonate aquifer (Craig and Robison 1984 
[DIRS 101040], p. 49). 
A6.3.6.6.1 Evidence for the Timing of Recharge from Hydrogen and Oxygen Isotope 
Ratios 
Many of the effects of seasonal and long-term temperature changes on hydrogen and oxygen 
values in groundwater described in Section A6.3.1.2.1 have been reported for the Yucca 
Mountain area. Benson and Klieforth (1989 [DIRS 104370], Figure 11) noted a correlation 
between d18O values and the 14C age of groundwaters near Yucca Mountain. Waters are lighter 
in d18O with increasing age between 9,000 and 18,500 years 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 years before the present (Winograd et al. 1992 [DIRS 100094], Figures 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 A6-48. The modern global meteoric water line 
(dD = 8 d18O + 10.0) shown on Figure A6-48 is approximately equal to the local Yucca 
Mountain meteoric water line (dD = 8 d18O + 8.9) as defined by Benson and Klieforth (1989 
[DIRS 104370], Figure 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. A 
paleometeoric water line of dD = 8 d18O +5.0 was suggested by White and Chuma (1987 
[DIRS 108871], pp. 573 to 574) to fit data from the Amargosa Desert and Oasis Valley. 
Although considerable variability in dD and d18O values is evident in Figure A6-48, much of this 
variability is attributable to the heavy dD and d18O values of the FMW-N samples and the light 
dD and d18O values of the TM samples. The Yucca Mountain groundwaters (YM groupings 
only) and most perched waters (excluding NRG-7a and one UZ-14 sample) vary in dD by 
about 13 per mil and in d18O by about 1 per mil. The high 14C activities associated with the 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-166 November 2004 
FMW-N groundwater and the low 14C activities associated with the TM groundwater suggest 
that some of the differences between the dD and d18O values in these groups is attributable to 
changes in the dD and d18O composition in response to climate change, with the heavy values 
representing the composition of groundwater recharged under the modern climate. 
Because the groundwaters shown in Figure A6-48 probably originated from different recharge 
areas and recharge elevations, the effects of climate-induced changes and these other factors are 
mixed. The effects of time- and climate-induced changes on dD and d18O composition can be 
isolated from these other effects by examining the changes in the composition of pore and 
perched water with depth in the unsaturated zone at Yucca Mountain (Figure A6-48). In this 
case, because all of the perched and pore-water data from borehole UZ-14 probably originated 
close to the borehole, the effects of spatial and elevation distributions of recharge are minimal. 
At borehole UZ-14, the pore-water data from borehole UZ-14 show a general trend of lighter dD 
and d18O in the deeper (Tac and Tcp) pore waters and heavier dD and d18O in shallow pore 
waters (PTn). The shallow pore water that results from infiltration at Yucca Mountain is similar 
in dD and d18O composition to the modern groundwater from upper Fortymile Canyon, 
suggesting that the dD and d18O composition of modern precipitation is similar in both locations. 
Note that none of the pore-water data in Figure A6-48 show systematic trends that indicate 
evaporative effects (Section A6.3.1.2.1, Figure A6-4). This observation suggests that the 
relatively high pore-water salinities observed in the shallow part of this borehole (Yang et al. 
1996 [DIRS 100194], Table 3), and perhaps other parts of Yucca Mountain, are due to plant 
transpiration rather than evaporation (Section A6.3.1.2.1). Other groundwaters from the Yucca 
Mountain area, like those in the FMW-S group, may indicate more significant evaporative 
effects (Figure A6-48). 
Perched waters from UZ-14 have dD and d18O compositions that are intermediate between the 
shallow and deep pore waters. The deep pore water from the relatively impermeable Tac unit is 
lighter than the pore water from the underlying, but more permeable Tcp unit, suggesting that it 
has been more difficult to flush the older, lighter pore water in the Tac with younger water 
(Yang et al. 1998 [DIRS 101441]). The pore-water data indicate that groundwater from the 
YM-C and YM-SE is similar in composition to the deep pore water from the Tac unit at borehole 
UZ-14, supportive of their possible origin from local recharge. The decrease in 
d18O composition of about 2 per mil between the shallow pore water and the deep pore-water and 
Yucca Mountain groundwater compositions from the YM-CR, YM-C and YM-SE groupings is 
comparable to the approximately 1.9 per mil differences in calcite d18O composition at Devils 
Hole (Winograd et al. 1992 [DIRS 100094], Figure 2) for glacial and subsequent interglacial 
periods, suggesting the deep pore water and Yucca Mountain groundwater were recharged under 
a paleoclimatic conditions that existed until the late Pleistocene. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-167 November 2004 
DTN: GS990308312272.002 [DIRS 145692. 
Source: Tables A6-2 and A6-5; pore-water data for borehole UZ-14 are from Yang et al. (1998 [DIRS 101441] 
Tables 912). 
NOTE: This figure has color-coded data points and should not be read in a black and white version. The solid lines 
are the global meteoric water line (dD = 8 d18O + 10) (Clark and Fritz 1997 [DIRS 105738], p. 36) and a 
possible paleometeoric water line for southern Nevada (dD = 8 d18O + 5) (White and Chuma 1987 
[DIRS 108871], pp. 573 to 574). 
Figure A6-48. Delta Deuterium and Delta 18O Data for Borehole UZ-14 Unsaturated Zone Pore Water, 
Perched Water, and Groundwater near Yucca Mountain 
In contrast, some of the YM-S area groundwater does not overlap with the deep pore-water data 
from the borehole, raising doubts as to whether it originated predominantly from 
Yucca Mountain recharge. Many groundwaters from the YM-S group, including Sites 91 
(NC-EWDP-2D) and 92 (NC-EWDP-19D composite) near Fortymile Wash are isotopically 
similar to groundwaters in the Crater Flat (CF) and Solitario Canyon Wash (SCW) groups. 
Groundwaters from Sites 93 (NC-EWDP-19P) and 96 (NC-EWDP-19D Zone 2) plot nearer to 
the deep pore water from borehole UZ-14. The remaining groundwater samples from 
NC-EWDP-19D (Sites 94, 95, 97, and 98) have no clear affinity with groundwater from other 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-168 November 2004 
areas. In general, it does not appear likely from the dD and d18O compositions that groundwater 
from wells NC-EWDP-2D or NC-EWDP-19D originated from present or paleorecharge along 
Fortymile Wash, based on the lack of overlap between data from these sites and data from the 
FMW-N and FMW-S groups. However, for groundwaters from Sites 93 (NC-EWDP-19P) and 
96 (NC-EWDP-19D Zone 2), the dD and d18O data do not obviously rule out an origin from 
paleorecharge along Fortymile Wash. 
A6.3.6.6.2 Evidence for the Timing of Recharge from Carbon Isotope Data 
As is discussed in Section A6.3.1, the 14C ages of groundwater are susceptible to modification 
through water-rock reactions. Nonetheless, various 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 36Cl to stable chlorine (36Cl/Cl) of the perched-water samples are 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 packrat midden data (Plummer 
et al. 1997 [DIRS 107034], Figure 3; DTNs: LAJF831222AQ97.002 [DIRS 145401], 
GS950708315131.003 [DIRS 106516], and GS960308315131.001 [DIRS 106517]). Second, 
Winograd et al. (1992 [DIRS 100094], Figure 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 A6-48). This consistent 
difference suggests that, at some boreholes, the perched water may contain a substantial 
component of water from the Pleistocene. 
Values for d13C and 14C in perched waters and groundwaters from the Yucca Mountain area are 
plotted in Figure A6-45. Excluding the perched-water and the Fortymile Wash area (FMW-N) 
samples, the d13C and 14C values reported for the groundwater samples are 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 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 A6-45. 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 A6-45. 
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 [DIRS 100073], 
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). The change from a relatively wet, cool climate to a relatively warm, dry 
climate at the end of the Pleistocene would be expected to exert a similar effect on the d13C of 
infiltration as elevation does on modern infiltration. In other words, Pleistocene infiltration 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-169 November 2004 
would be expected to have lighter d13C than modern infiltration at the same elevation. However, 
both a climate induced change in d13C values, or recharge from a distant, high-elevation source 
would result in a positive correlation in Figure A6-45 because the older samples (that is, lowest 
pmc) plotted would tend to have the most negative d13C (that is, they infiltrated when the climate 
was cooler than it is now or in distant, high-elevation areas). 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). Both calcite dissolution and mixing with groundwater from the 
carbonate aquifer are possible explanations for this observed trend. Both of these processes 
would tend to introduce DIC with heavy d13C and little 14C. The importance of each process 
probably varies spatially and can be assessed by determining if increases in other ions and 
isotopes present at high concentrations in the carbonate aquifer are evident in the groundwater. 
A likely cause of the negative correlation evident in Figure A6-45 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 A6-45. 
The data points for groundwater from the FMW-N grouping with high 14C activities 
(Sites 30 to 32) are of particular interest because they represent recent infiltration based on their 
high tritium and 36Cl-to-chloride ratios (DTN: LAJF831222AQ98.011 [DIRS 145402]). As 
shown in Figure A6-45, the 14C activities in these samples vary between 60 and 75 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 [DIRS 137305], Figure 5). 
In instances where the recharge source for a groundwater can be identified, it is possible to 
estimate the extent to which the 14C activity of the groundwater has been lowered through 
water/rock interactions in the saturated zone by comparing the DIC concentrations of the 
recharge (DICrech) and the downgradient groundwater (DICgw) (Clark and Fritz 1997 
[DIRS 105738], Chapter. 8). The downgradient increase in DICgw relative to DICrech represents 
the extent to which mineral sources of carbon have been added to the groundwater. These 
mineral sources of carbon may have diluted the initial 14C activity of the recharge by the addition 
of 14C-free carbon. The extent of this dilution and its effect on the calculated groundwater 
14C age can be represented by a correction factor (qDIC = DICrech/DICgw) which is then applied to 
the radioactive decay equation to calculate the corrected 14C age, as indicated in footnote (b) to 
Table A6-9. The basis for the equations given in footnote (b) and their limitations are described 
in more detail in Section A6.3.9. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-170 November 2004 
As described in Sections A6.3.6.2 to A6.3.6.4, evidence exists that some groundwater samples 
from Yucca Mountain originated almost exclusively from recharge through Yucca Mountain 
itself. Corrections were made to groundwater 14C ages at locations within 18-km of the 
repository where groundwater had been identified from anomalously high 234U/238U ratios as 
having originated mostly from local recharge (Paces et al. 1998 [DIRS 100072]; see also 
Table A6-5). Corrections were also made to the 14C ages of groundwater from several locations 
for which 234U/238U activity ratios were not measured, but which may contain substantial 
fractions of local Yucca Mountain recharge based on proximity to groundwater with high 
234U/238U activity ratios. For these samples, total DIC concentrations, calcite saturation indices, 
and logarithms of the partial pressure of carbon dioxide (log PCO2) were computed with 
PHREEQC (DTN: MO0309THDPHRQC.000 [DIRS 165529]). In these corrections, the values 
of DICrech are allowed to vary between 128.3 and 144 mg/L bicarbonate (HCO3
), based on 
values measured in perched water at Yucca Mountain (Yang et al. 1996 [DIRS 100194]; 
Table A6-5). The correction factor qDIC ranges from 0.74 at borehole WT#12 to 1.0 at several 
boreholes (Table A6-5). Corrected groundwater 14C ages range from 11,430 years at borehole 
WT#3 to 16,390 years at borehole WT#12 (Table A6-7). These calculations show that only 
minor corrections to the groundwater 14C ages are necessary for samples located along the 
estimated flow path from the repository (see below). 
Table A6-7. Chemistry and Ages of Groundwaters from Seven Boreholes at Yucca Mountain 
Borehole 
234U/238U 
Activity 
Ratio 
14C Activity 
(pmc) 
DIC, as 
HCO3
 
(mg/L) 
log PCO2 
(atm) 
log 
(IAP/Kcal)a 
Factor 
qDIC 
Corrected 14C 
Age(yr)b 
Uncorrected 
14C Age (yr)c 
G-2 7.6 20.5 127.6 -2.352 -0.791 1 13,100 13,100 
WT-17 7.6 16.2 150.0 -1.958 -1.175 0.860.96 13,750 
14,710 15,040 
WT#3 7.2 22.3 144.3 -2.413 -0.515 0.891.0 11,430 
12,380 12,400 
WT#12 7.2 11.4 173.9 -2.327 -0.313 0.740.83 15,430 
16,390 17,950 
c#3 8.1 15.7 140.2 -2.458 -0.319 0.921.0 14,570 
15,300 15,300 
b#1 (Tcb)d  18.9 152.3 -1.892 -0.757 0.840.95 12,350 
13,300 13,770 
G-4  22.0 142.8 -2.490 -0.305 0.901.0 11,630 
12,510 12,500 
DTN: LA0202EK831231.002 [DIRS 165507]. 
Source: Tables A6-1 and A6-2; 
a log (IAP/Kcal) is the calcite saturation index. Negative values indicate undersaturation with calcite. 
b The corrected age is calculated by multiplying the initial 14C activity (14A0) in Equation A6-3 by qDIC: t = (-1/.) ln 
(14A/(14A0 qDIC)). The factor qDIC is calculated as qDIC = DICrech/DICgw, where the subscripts rech and gw indicate 
the DIC of recharge and downgradient groundwater. 
c Calculated from Equation A6-3. 
d The sample from borehole b#1 came from the Bullfrog tuff (Tcb). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-171 November 2004 
A6.3.6.7 Calculations to Determine the Fraction of Young Water in Yucca Mountain 
Recharge 
Given that groundwater samples at Yucca Mountain were often pumped over large depth 
intervals that mixed shallow and deep water (Table A4-3), it may be difficult to demonstrate 
conclusively that groundwater does not contain a small fraction of young water. In this section, 
however, calculations are performed to bound the maximum percentage of young water that 
could be present in the sampled groundwater. 
Recharge at Yucca Mountain has probably been continuous in time, so that the measured 
groundwater 14C activities result from the mixing of recharge (and possibly groundwater from 
other areas) having a broad range of ages (Campana and Byer 1996 [DIRS 126814], Figure 5). 
However, because data on the temporal distribution of recharge, mixing depth, and storage 
volume required for more detailed analyses are lacking, the fraction of young water in a 
groundwater sample is calculated in this section by idealizing individual groundwater samples as 
a binary mixture of younger and older groundwaters. Young water is arbitrarily defined as 
having a 14C age, or residence time, of less than 1,000 years. In a binary mixture, the total 
number of 14C atoms in the mixture depends on the 14C activities, volume fractions, and total 
DIC concentrations of the two components, which in this case, are taken to be young and old 
waters: 
(14Cmix)(DICmix) = (Xyoung)(14Cyoung)(DICyoung) + (Xold)(14Cold)(DICold) (Eq. A6-8) 
where 
14C = the 14C activity (in pmc) 
DICi = dissolved inorganic carbon concentration (mg/L) of component i 
Xi = the volume fraction of component i 
mix, young, and old = mixed, young, and old components of the groundwater. 
The volume fractions sum to one, so that Xold = 1  Xyoung. Equation A6-8 can be solved for 
Xyoung: 
Xyoung = (14Cmix ) (DICmix ) - (14Cold ) (DICold ) 
(14Cyoung) (DICyoung ) - (14Cold ) (DICold ) 
(Eq. A6-9) 
The 14C activity of 1,000-year-old water with an initial 14C activity of 100 pmc is equal 
to 88.6 pmc. DICyoung is expressed in these calculations as equivalent to mg/L HCO
3 and is 
assigned a value of 130 mg/L based on the typical alkalinity of many perched-water samples 
(Table A6-5). For samples with pH values above 7, which include perched water from the 
unsaturated zone at Yucca Mountain, alkalinity is approximately equal to the total DIC (Drever 
1988 [DIRS 118564], p. 51). The value for 14Cold was assigned a value of 10 pmc, which is 
approximately the lowest value measured in groundwater from the volcanic aquifer at Yucca 
Mountain (boreholes H-3 (10.5 pmc) and H-4 (11.8 pmc)). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-172 November 2004 
Calculations of the possible fraction of young water in a sample (age less than 1,000 years) 
considered various DIC concentrations for the old component in the mixed water (Table A6-8). 
In Case 1, the DIC concentrations of the water components (mixed, old, and young) are assigned 
to be essentially equal, so that Xyoung depends only on values of 14C. In Case 2, a moderately 
high value of 175 mg/L HCO3
 was assigned for DICold. In Case 3, a value of 
225 mg/L HCO3
- was assigned for DICold. For Case 1, the calculated values of Xyoung range from 
about 0.02 (borehole WT#12) to 0.16 (boreholes WT#3 and G-4). For Case 2, the range of 
values for Xyoung is similar to, but slightly lower than, those from Case 1. In Case 3, the 
calculated values for Xyoung were lower than those from Cases 1 and 2, and three values were 
negative, which indicates that the value of 225 mg/L HCO3
 for DICold was too high to be 
generally applicable. 
Table A6-8. Sensitivity of the Permissible Fraction of Young Water Present in Groundwater to Dissolved 
Inorganic Carbon Concentration Assumed for the Old Component of the Mixed 
Groundwater 
Borehole 
Sample 14C 
(pmc) 
Sample DIC 
(mg/L HCO3
) 
Xyoung 
(Case 1)* 
Xyoung 
(Case 2)* 
Xyoung 
(Case 3)* 
G-2 20.5 127.6 0.134 0.089 0.039 
WT#12 11.4 173.9 0.018 0.024 -0.029 
WT-17 16.2 150.0 0.079 0.070 -0.019 
WT#3 22.3 144.3 0.156 0.150 0.104 
c#3 15.7 140.2 0.073 0.046 -0.005 
b#1 (Tcb) 18.9 152.3 0.113 0.116 0.068 
G-4 22.0 142.8 0.153 0.142 0.096 
Output DTN: LA0202EK831231.004. 
Source: Tables A6-1 and A6-2 
NOTES: Table values were calculated based on data in Tables A6-1 and A6-2, Equation A6-9, and 
parameter values given in the text. Young groundwater is defined as less than 1,000 year old. 
*Case 1: DICold = DICyoung = DICmix; Case 2: DICold = 175 mg/L HCO3
; Case 3: DICold = 225 mg/L HCO3
-. 
Sensitivity studies were conducted to examine the effects of assigning variable values of 14Cold 
with DICold = 175 mg/L HCO3
. Results of these studies show that the calculated values of 
Xyoung are somewhat sensitive to the value of 14Cold (Table A6-9). Using 14Cold = 5 pmc (Case 4) 
more than doubles the calculated value of Xyoung at many boreholes; however, values 
less than 10 pmc have not been observed at Yucca Mountain, so a value for 14Cold of 5 pmc is 
considered unrealistic. A value for 14Cold of 15 pmc (Case 5) is also generally unrealistic, given 
the many negative values calculated for Xyoung. 
In summary, it is possible that a small fraction of young water (less than 1,000-year-old) is 
present in the saturated zone downgradient from the repository area. Estimates range from a low 
of about 0.02 at borehole WT#12 to more than 0.15 at boreholes WT#3 and G-4. Smaller 
fractions of young water would be estimated to be present if water younger than 1,000-year-old 
were assumed in the calculations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-173 November 2004 
Table A6-9. Sensitivity of the Permissible Fraction of Young Water Present in Groundwater to the 
Assumed 14C Activity of the Old Component of the Mixed Groundwater 
Borehole 
Sample 14C 
(pmc) 
Sample DIC 
(mg/L HCO3
) 
Xyoung 
(Case 4)* 
Xyoung 
(Case 2)* 
Xyoung 
(Case 5)* 
G-2 20.5 127.6 0.164 0.089 -0.001 
WT#12 11.4 173.9 0.104 0.024 -0.072 
WT-17 16.2 150.0 0.146 0.070 -0.022 
WT#3 22.3 144.3 0.220 0.150 0.067 
c#3 15.7 140.2 0.125 0.046 -0.048 
B#1 (Tcb) 18.9 152.3 0.188 0.116 0.029 
G-4 22.0 142.8 0.213 0.142 0.058 
Output DTN: LA0202EK831231.004. 
Source: Tables A6-1 and A6-2. 
NOTES: Table values were calculated based on data in Tables A6-3 and A6-4, Equation A6-9, and 
assumptions given in the text. Young groundwater is defined as less than 1,000-year-old. 
*Case 4: 14Cold = 5 pmc; Case 2: 14Cold = 10 pmc; Case 5: 14Cold = 15 pmc. 
A6.3.7 Hydrochemical Evidence for Mixing of Groundwater 
Groundwater chemical and isotopic compositions in the Yucca Mountain area exhibit both 
gradual and relatively abrupt spatial variability (Section A6.3.4) that may be related to mixing. 
Mixing may occur when (1) groundwater from adjacent flow paths is spread by dispersion and 
diffusion, (2) the groundwater passes beneath a recharge area, (3) deep groundwater moves 
upward because of head gradients, faults, or hydraulic barriers, or (4) groundwater from different 
areas converges toward either natural discharge areas or toward wells. Preliminary mixing 
relations are investigated in this section through scatterplots involving relatively nonreactive 
chemical and isotopic species like Cl, SO4
2, dD, and d34S. Potential mixing relations identified 
through these scatterplots are further explored through the use of inverse geochemical models in 
Section A6.3.8 that seek to quantitatively explain groundwater chemical and isotopic evolution 
in terms of mixing and water-rock interactions. 
A6.3.7.1 Mixing Relations South of Yucca Mountain 
Groundwater samples from boreholes located south of Yucca Mountain that constitute the 
YM-S, CF, and CF-SW groupings show a wide range of solute concentrations that generally 
increase to the northwest. Scatter plots (Figure A6-49) illustrate the distinct hydrochemistry of 
groundwater affected by carbonate rocks (CF-SW, p#1(c)) when compared to groundwater from 
the volcanic or tuff-derived alluvial aquifers. In fact, samples from the CF-SW group define a 
trend with a dilute end member intersecting typical groundwater compositions of the volcanic 
aquifer at Yucca Mountain. Importantly, some samples from the YM-S group fall along this 
line. In the YM-S group, groundwaters from borehole NC-EWDP-9SX (Samples 81 to 85) are 
most similar to samples from the CF-SW group chemically and are also geographically proximal 
to the CF-SW wells to the north and west. It is interpreted that the hydrochemistry of samples 
from borehole NC-EWDP-9SX represents a mix of carbonate aquifer-like water from southwest 
Crater Flat and dilute groundwater from the volcanic aquifer. Samples 89 and 90 also plot along 
mixing lines between the volcanic aquifer and the carbonate aquifer-like groundwaters. Given 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-174 November 2004 
the geographic position of these wells, it is unclear as to whether this carbonate aquifer-like 
water enters the system via upward gradient flow from depth or if it could be due to dispersive 
mixing of groundwater from the CF-SW Group. On the Cl versus dD plot (Figure A6-49) 
groundwater from the YM-S group define a trend toward the CF-SW group, not toward the 
composition of p#1 or deep groundwater from NC-EWDP-1DX Zone 2 (Site 74), indicating 
dispersive mixing rather than groundwater upwelling as the more likely hypothesis. The 
Cl- versus dD plot (Figure A6-49) also helps to eliminate the possibility that the compositional 
trends defined by these samples are due to water/rock interaction with alluvium that is 
increasingly dominated by carbonate detritus derived from Bare Mountain because dD is not 
affected by this process. 
A6.3.7.2 Evaluation of Mixing Relationships in the Amargosa Desert Region 
The different groundwater groupings in the Amargosa Desert display a great contrast in solute 
concentration and isotopic data (Section A6.3.4). Indeed, much of the hydrochemical variation 
displayed in areal plots of chemical and isotopic species is contained in the relatively small area 
of the Amargosa Desert. This pronounced contrast in hydrochemistry, along with the relatively 
dense sample distribution allows for detailed evaluation of possible mixing patterns. 
Groundwater in the AR grouping is chemically quite distinct with relatively large concentrations 
of solutes compared to groundwater to the east in Amargosa Desert, and thus, it is readily 
distinguishable and traceable. East and southeast of the AR grouping the consistent and distinct 
character of this groundwater is absent. Mixing with the dilute groundwater that constitutes the 
FMW-W and FMW-S groupings readily explains this observation. On a plot of the conservative 
solutes Cl and SO4
2 (Figure A6-50) the hydrochemically distinct groupings of the AR and 
FMW-S groupings is evident along with the trend displayed by some samples of the FMW-W 
group and all of the samples from the AR/FMW grouping. This relationship is taken as sound 
evidence that intermediate Cl and SO4
2 compositions of FMW-W and AR/FMW are a result of 
mixing of Amargosa Desert groundwater with dilute groundwater of the FMW-W grouping 
and/or FMW-S grouping (shown as mixing line 1, Mix 1, in Figure A6-50). This hypothesis is 
also supported by cross plots of other constituents. For example, although the number of 
samples is limited, Figure A6-51 shows the mixing relationships on a plot of 
d34S versus 1/SO4
2-. On this plot, the few samples from FMW-W and AR/FMW are near the 
mixing line drawn between the FMW-S and AR samples (Mix 1). Scatter plots of other 
constituents show similar relations, although some deviations from the consistent trend displayed 
in Figure A6-50 suggest that water-rock interaction has modified the hydrochemistry in some 
samples. Hydrochemical data are interpreted to indicate that samples 121, 122, 125, and 
126 (FMW-W) and most samples from the AR/FMW group represent mixtures of 
AR groundwater with FMW-S and/or dilute groundwater from FMW-W. Samples 139 and 134 
from FMW-S also plot along mixing line 1 (Figure A6-50) suggesting that these samples also 
contain a small fraction of AR groundwater. These samples are among the more westerly in this 
grouping; thus, the geographic position is consistent with this mixing hypothesis. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-175 November 2004 
Source: Tables A6-1 and A6-2. 
NOTE: The plots on the right side of this figure have expanded scales compared to similar plots directly to their left 
to better display details in the tightly clustered data. 
Figure A6-49. Scatter Plots Showing Mixing in Southern Yucca Mountain 
MDL-NBS-HS-000011 REV 02 A-176 November 2004 
Saturated Zone Site-Scale Flow Model 
Source: Table A6-1. 
NOTES: Mixing lines show 10 percent increments. End members for the mixing lines are: dilute end member for all mixing lines is 6.5 mg/L Cl and 22 mg/L 
SO4
2. Mixing line 1 (Mix 1) upper end member is the average of the AR Group of 73 mg/L Cl and 200 mg/L SO4
2. Mixing line 2 (Mix 2) upper end 
member corresponds to Cl and SO4
2 values for J-11 of 17.5 mg/L and 480 mg/L, respectively. Mixing line 3 (Mix 3) upper end member is the visual 
average of the tight cluster displayed by the GF Group (Cl and SO4
2 concentration of 28 mg/L and 160 mg/L, respectively). Mixing lines are drawn by 
plotting calculated values for Cl and SO4
2 obtained by the mixing equation: [Cl]mix = F[Cl]A +(1  F)[Cl]B, where F is the fraction of component A in 
the mix. The SO4
2 concentration is determined by substituting values for SO4
2 into the equation. 
Figure A6-50. Cross Correlation Plot of Sulfate versus Chloride for Samples in the Amargosa Desert Region 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-177 November 2004 
Samples 119, 120, 123, and 124 are the most dilute groundwaters from the FMW-West grouping. 
Three of four of these are also the most northeasterly wells of the grouping, furthest from the 
flow pathway of the AR group groundwater. Samples 118, 121, 122, 125, and 126 are located to 
the south or southwest of the dilute samples and show variable amounts of mixing with 
Amargosa River groundwater. This pattern is consistent with southeastward groundwater flow 
from the vicinity of the AR group. The relative amounts of mixed Amargosa River water are not 
entirely consistent with geographic position, however. Similar to the FMW-W grouping, the 
mixing percentages for wells of the AR/FMW group do not correlate with geographic position. 
In fact, the Cl and SO4
2 concentrations of samples 118 and 181 are essentially identical to those 
of the AR group, and these are located adjacent to wells with significantly different anion 
concentrations. This inconsistency in detailed correlation between hydrochemistry and 
geographic position may be due to factors that are unknown or poorly understood including well 
completion, well pumping history, and vertical and horizontal anisotropy in the flow system. 
The similar hydrochemistry of well 181 compared to that of the AR group suggests a continuous 
flow pathway between these areas. Doing so, however, isolates sample 179, which clearly plots 
as a mixed sample with most of this water similar to the dilute water of the FMW-S group, and 
geographically separates a mixed sample from one of its presumed sources. Again, this 
inconsistency may be related to vertical heterogeneities or potentially points to another dilute 
groundwater source in southwestern Amargosa Desert. Although a pristine AR end member 
groundwater has not been sampled south of well 181, the mixing relationship demonstrated by 
samples 183 to 185 allows continuation of the flow pathway to the west of these samples. 
Groundwater from the Gravity fault group also has a distinct Cl and SO4
2 concentrations, 
although the group does show some variability (Figure A6-50). A mixing line between average 
Cl and SO4
2 concentrations for the tight cluster of the GF and FMW-S group samples is shown 
on Figure A6-50 (Mix 3). Groundwaters from the LW and FMW-E groups define an array 
along, though slightly above, this mixing line. These two groups of wells also lie geographically 
between the two hydrochemical end-member groups. This relationship suggests that the 
intermediate chemical compositions of the LW and the FMW-E groups may be due to mixing of 
variable amounts of dilute water from the Fortymile Wash and groundwater from the GF group. 
Analysis of other constituents, however, suggests that an additional component may be present. 
As mentioned, samples of the LW and FMW-E groups plot along but above the mixing line 
between the GF samples and the FMW-S samples. In fact, these samples plot intermediate 
between this mixing line (Mix 3) and a mixing line (Mix 2) between the FMW-S samples and 
well J-11, which has Cl and SO4
2 concentrations of 17.5 mg/L and 480 mg/L, respectively 
(Figures A6-32 and A6-33, Table A6-1). It is possible, given this relationship and the relative 
geographic position of these well groupings that some groundwater from the vicinity of well 
J-11 (Site 67) has mixed with these samples. On the plot of d34S and 1/SO4
2 (Figure A6-51), the 
few samples from the LW group and the FMW-E group form a trend between the FMW-S 
samples and groundwater from well J-11. This trend is strongly suggestive of a mixing 
relationship between these samples. Mixing calculations using Cl, SO4
2, and d34S indicate that 
a maximum of approximately 20 percent J-11 water is present in one of these samples (site 
101the Desert Farms Garlic Plot well). Sample 141 (FMW-S) contains elevated SO4
2 for the 
measured Cl concentration and plots along mixing line 3. The geographic position and 
hydrochemistry of this sample are consistent with it containing a small percentage of J-11-like 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-178 November 2004 
water. The data plotted in Figure A6-51 do not support the hypothesis that groundwater from the 
LW and FMW-E groups contains a component of GF water, although the data set for d34S is 
incomplete. 
Many of the GF samples are also collinear with some samples from FMW-E and LW groups 
(Figure A6-50). For example, samples 160, 174, and 175 plot intermediate between the tight 
cluster of GF samples and dilute groundwater of the FMW-S, FMW-E, and LW groups. These 
samples are also among the more westerly of the GF samples, located geographically between 
groundwater that defines the tight cluster of GF samples and the FMW-E samples. These 
samples are also interpreted to be mixtures of GF groundwater and more dilute water of the 
FMW-E group. 
Source: Tables A6-1 and A6-2. 
NOTES: On this diagram, a mixture plots as a straight line. Mixing lines show 10 percent increments. End 
members for the mixing lines are: 24 mg/L SO4
2 and 9.65 per mil d34S for the dilute end member. Mixing 
line 1 (Mix 1) upper end member is the visual average of the AR group samples of 160 mg/L SO4
2 and 
22 per mil d34S. Mixing line 2 (Mix 2) upper end members corresponds to SO4
2 and d34S values for J-11 
of 480 mg/L and 8.8 per mil, respectively. Mixing lines are drawn by plotting calculated values for SO4
2 
and d34S obtained by the mixing equations: [SO4
2]mix = F[ SO4
2]A + (1  F)[ SO4
2]B, where F is the 
fraction of component A in the mix. Delta sulfur-34 is determined by: [ d34S] mix = (F[SO4
2]A d34SA + 
(1  F)[SO4
2]B d34SB)/[SO4
2]mix. 
Figure A6-51. Scatter Plot of Delta 34S versus Inverse Sulfate for Samples in the Amargosa Desert 
Region 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-179 November 2004 
A6.3.8 Groundwater Mixing and Reaction Analyses Using PHREEQC 
In general, the chemical and isotopic composition of groundwater results from the mixing of 
groundwater from various upgradient locations as well as water-rock interaction along the 
individual flow paths. Groundwater mixing can occur naturally as a result of hydrodynamic 
dispersion and can also be induced during groundwater pumping. In either case, however, 
groundwater mixing can result in real or apparent changes in the composition of even 
nonreactive chemical and isotopic species in a downgradient direction. 
A number of inverse groundwater mixing and reaction analyses were performed to help identify 
both the upgradient groundwaters that could be present in a downgradient groundwater and the 
chemical reactions required to explain the downgradient changes in the composition of reactive 
species. The groundwaters that are considered as potential components in the downgradient 
groundwater are identified from relatively nonreactive species such as Cl, SO4
2, dD, d18O, and 
d34S. The composition of these species in the downgradient groundwater is assumed to result 
only from mixing of upgradient groundwaters. The remainder of the chemical and isotopic 
species, including other major and minor ions, dissolved SiO2, and dissolved carbon isotopes, are 
considered in these models to result both from mixing and from water-rock interaction. After 
first determining the mixing fractions of the potential components from the nonreactive species, 
PHREEQC adjusts the amounts of reactive chemical and isotopic species in the mixture by 
finding some combination of the allowable reactions that satisfy the mass balance constraints for 
each chemical and isotopic species. The consideration of reactive species limits the number of 
potential mixing analyses to those for which plausible chemical reactions can also be found. 
The potential groundwater components in the mixture were identified from contour maps of 
hydraulic heads (Figure A6.5-1) and areal plots and scatterplots between the aforementioned 
nonreactive chemical and isotopic species. For groundwaters in the volcanic or alluvial aquifers, 
upgradient groundwater could include recharge as well as groundwater in the carbonate aquifer, 
which at Yucca Mountain has a higher hydraulic head than groundwater in the volcanic aquifer. 
The geographic distribution of one or more nonreactive species in a downgradient direction as 
shown on maps in Section A6.3.4 suggests an initial combination of groundwaters that may lie 
along a flow path. In some parts of the Yucca Mountain area where only slight differences in 
solute concentrations exist among wells, scatterplots of both nonreactive and reactive species 
were used to suggest possible combinations of groundwaters that may be involved in a mixture 
(Sections A6.3.6.3 and A6.3.7). 
The chemical reactions considered in these PHREEQC; (DTN: MO0309THDPHRQC.000 
[DIRS 165529]) mixing and reaction analyses are restricted to those that are consistent with 
known ion-exchange reactions and mineral saturation indices. Generally, pore-water data from 
Yucca Mountain (Yang et al. 1996 [DIRS 100194]; 1998 [DIRS 101441]) and Rainier Mesa 
(White et al. 1980 [DIRS 101166]) indicate that Ca2+, Mg2+, and K+ in solution are exchanged 
for Na+ initially on the exchange sites of minerals. The saturation indices calculated in 
Section A6.3.5 indicate that Ca-clinoptilolite, Na-clinoptilolite, and smectite may precipitate 
from groundwater in some areas. Conversely, plagioclase, K-feldspar, calcite, fluorite, kaolinite, 
and amorphous silica are potentially dissolved by groundwater in certain parts of the Yucca 
Mountain area. Measurements of CO2(g) in the unsaturated zone at Yucca Mountain indicate a 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-180 November 2004 
log PCO2 of about 3.0 (Yang et al. 1996 [DIRS 100194], Figure 18b). Groundwater with 
calculated log PCO2 greater than 3.0 will therefore potentially degas into the overlying 
unsaturated zone when the log PCO2 of the groundwater is greater than 3.0 and vice-versa. 
A summary of the mineral phases considered in the PHREEQC analyses, their chemical 
formulas, and any constraints imposed on their precipitation or dissolution is summarized in 
Table A6-10. Unless otherwise noted in Table A6-12, all mineral phases were considered as 
potential reactants or products in each PHREEQC analyses discussed in this section. 
The inverse analyses identified by PHREEQC are required to simultaneously satisfy 
mass-balance constraints for pH and for each element contained in the phases listed in 
Table A6-10. Where the inverse analyses consider groundwater mixing, the proportions of 
groundwater from various upgradient wells in the mixture are identified from nonreactive 
elements or isotopes that, by definition, are not contained in the list of reactive phases. These 
additional nonreactive elements and isotopes include Cl and, depending on the model, dD and 
d18O. Many of the inverse models were also required to satisfy mass-balance constraints for 
d13C, which made it necessary to specify values of 14C and d13C for the C-bearing phases in these 
models (Table A6-10, Note 7). 
The groundwater concentrations and isotopic compositions, as well as the isotopic compositions 
of the gas and mineral phases, are assumed by PHREEQC to be somewhat uncertain because of 
laboratory analytical error and because of uncertainty associated with the effects of well drilling, 
completion, and development on groundwater sample compositions. The specified uncertainties 
varied, depending on the parameter and the model. In general, the specified uncertainties were 
as follows: pH (0.05 pH units), ions (10 percent of the measured concentrations), d13C 
(0.1 per mil), d18O (0.1 per mil), and dD (1.0 per mil). These uncertainties determined the 
amount by which the measured chemical or isotopic parameters in each solution could be 
adjusted by PHREEQC to obtain mass balance for that parameter. In some cases, however, if no 
convergent analyses were identified because of a mass imbalance for a single chemical or 
isotopic species, the specified uncertainties for that species were increased from their typical 
values until a model, or set of models, could be found. For example, in one set of models, the 
specified uncertainty for d13C was increased to 0.5 per mil, and in another set, the uncertainty in 
d18O was increased to 0.4 per mil. In several sets of analyses, it was necessary to increase the 
uncertainty in F- to 20 percent or more of the measured concentrations, effectively eliminating Fas 
a chemical constraint for that set of models. For a subset of models, it was necessary to 
consider dissolution of kaolinite to balance Al3+ concentrations; generally, however, Al3+ 
concentrations could be balanced using the other alumino-silicate minerals. 
Additional uncertainty associated with these analyses results from the variability in mineral 
compositions, nonideal chemical compositions for common rock forming minerals like 
K-feldspar and calcites, and the nonuniqueness of the inverse models themselves. As 
demonstrated in the following sections, it is often possible to find several combinations of wells 
and sets of water/rock interactions that can explain the chemical and isotopic composition of 
groundwater in the downgradient well. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-181 November 2004 
Table A6-10. Mineral Phases and Exchange Reactions Considered in the PHREEQC Inverse Analyses 
Phase or 
Exchange 
Cation Formula in PHREEQC Analyses1 Constraint Formula Reference 
Carbon 
dioxide7 CO2 Exsolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Calcite7 CaCO3 
Dissolution or 
precipitation2 
Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Plagioclase Na0.8Ca0.2Al1.2Si2.8O8 Dissolution only Vaniman et al. (1996 [DIRS 105946], 
Figure 1.22) 
K-feldspar KAlSi3O8 Dissolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Ca exchange CaX2 
Sorption only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Mg exchange MgX2 Sorption only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Na exchange NaX De-sorption only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
K exchange KX None Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Amorphous 
silica SiO2 Dissolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Kaolinite Al2Si2O5(OH)4 None3 Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Smectite K0.1Na0.02Ca0.14Al4.4Si7.6O20(OH)44H2 
O 
Precipitation 
only 
Chipera et al. (1995 [DIRS 100025], 
Table 1) 
Ca- 
Clinoptilolite4 
K2.5Na1.1Ca1.2Al6.0Si30.0O72.026.8 
H2O 
Precipitation 
only 
Chipera and Bish (1997 
[DIRS 105079], Tables 12) 
Na- 
Clinoptilolite4 
K2.8Na1.5Ca0.9Al6.1Si29.9O72.026.8 
H2O 
Precipitation 
only 
Chipera and Bish (1997 
[DIRS 105079], Tables 12) 
Pyrite FeS2 Dissolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Biotite KMg2FeAlSi3O10(OH)2 Dissolution only Vaniman et al. (1996 [DIRS 105946], 
Figure 1.22) 
Gypsum CaSO42H2O Dissolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Oxygen O2 None3 Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55 
Ferrihydrite Fe(OH)3 (a) Precipitation Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-182 November 2004 
Table A6-10. Mineral Phases and Exchange Reactions Considered in the PHREEQC Inverse Analyses 
(Continued) 
Phase or 
Exchange 
Cation Formula in PHREEQC Analyses1 Constraint Formula Reference 
Fluorite5 CaF2 Dissolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
Dolomite6,7 CaMg(CO3)2 Dissolution only Parkhurst and Appelo, (1999 
[DIRS 159511], Table 55) 
NOTES: 
1 An X in a formula in this column represents the exchange site. 
2 A dissolution constraint for calcite was imposed for all inverse models except for models involving the Desert 
Farms Garlic Plot well, for which a precipitation constraint was imposed for calcite. 
3 Although no precipitation (or exsolution) or dissolution constraints were imposed, none of the inverse models 
required the precipitation of kaolinite or the exsolution of O2. Kaolinite dissolution was considered only in models 
for wells NC-EWDP-3D, WT-3, and certain depth intervals of NC-EWDP-19D, for which it was necessary to 
balance Al3+ concentrations in the inverse models. Although groundwaters are assumed to be in equilibrium with 
kaolinite, kaolinite dissolution can be driven by the precipitation of smectite and clinoptilolite phases from the 
groundwater. 
4 Either Ca-clinoptilolite or Na-clinoptilolite, but not both, were considered in each inverse model. In the inverse 
models, the relevant clinoptilolite composition was determined by geography, with models for wells having 
potential upgradient sources in Crater Flat or Solitario Canyon assigned Na-clinoptilolite as a possible secondary 
phase and inverse models involving wells in central or eastern Yucca Mountain or near Fortymile Wash assigned 
Ca-clinoptilolite as a potential secondary phase. These choices were based on trends in clinoptilolite 
composition noted by Broxton et al. (1987 [DIRS 102004], Figure 8). 
5 Fluorite dissolution was considered only in a subset of inverse models, including those models with wells VH-1, 
WT-3, NC-EWDP-15P, GEXA Well 4, NC-EWDP-3D, and NC-EWDP-1S as the downgradient wells. 
6 Dolomite dissolution was considered only in a subset of inverse models where the proximity to dolomite outcrops 
or to alluvium derived from these outcrops had a possible influence on groundwater composition. These inverse 
models included those models with wells VH-1, GEXA Well 4, NC-EWDP-9S, NC-EWDP-3D, or NC-EWDP-1S 
as the downgradient well. 
7 The inclusion of d13C as a mass-balance constraint requires that the 14C and d13C of carbon-bearing phases 
(CO2, calcite, and dolomite) be defined. The 14C activity of any CO2 de-gassing from groundwater was set equal 
to the 14C of the groundwater at the downgradient well, and the 14C of the calcite and dolomite (if present) were 
set to 0. The d13C of CO2 de-gassing from the groundwater was assumed to be 18  2 per mil, based on 
measurements of the d13C of CO2 in the unsaturated zone at Yucca Mountain (Yang et al. 1996 [DIRS 100194], 
Figure 19). Except for the WT-3 models for which d13C was set to 1  3 per mil, the d13C of saturated-zone 
calcite in the volcanic and alluvial aquifers was set to 4  3 per mil, and the d13C of dolomite was set to 0  2 per 
mil, based on data for SZ calcites contained in Whelan et al. (1998 [DIRS 108865], p. 179 and Figure 2). 
A6.3.8.1 Desert Farms Garlic Plot 
The PHREEQC analyses investigated if groundwater at the Desert Farms Garlic Plot (DFGP) 
well (Site 101) could be produced by a mixture of groundwater from Fortymile Wash at borehole 
JF-3 (Site 37) and groundwater from Jackass Flats at well J-11 (Site 67). This PHREEQC 
analyses was motivated by the similar d34S and d13C ratios and low HCO3
 at both J-11 and the 
DFGP well, and by the mixing relation estimated from d34S versus 1/SO4
2, which indicated well 
J-11 and wells from the FMW-S area as potential mixing end members (Figures A6-50 
and A6-51). The 6 analyses identified by PHREEQC are of the form: 
DFGP well = X1 JF-3 + X2 J-11  calcite + plagioclase + SiO2(a) + K-feldspar  smectite  Caclinoptilolite 
+ biotite + pyrite + O2 (g)  Fe(OH)3(a)  MgX2  KX + NaX 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-183 November 2004 
where the fraction of well JF-3 groundwater (X1) is between 0.76 and 0.77 and the fraction of 
well J-11 groundwater (X2) is between 0.23 and 0.24. (Note that in these PHREEQC analyses 
the + indicates the phase was taken in solution along the flow path and  indicates the phase 
left the solution along the flow path. The X indicates phases on exchange sites.) Subsets of 
the phases indicated in the preceding reaction were identified in 6 reaction analyses by 
PHREEQC for this group of wells. Calcite precipitation was considered as a possible reaction 
because the groundwater at well J-11 is saturated with calcite (Figure A6.3-34). These mixing 
analyses did not use d34S as a constraint, but these mixing fractions are nonetheless in good 
agreement with the mixing fractions for Fortymile Wash area groundwaters and well J-11 
groundwater estimated using mixing trends based on d34S versus 1/SO4
2 (Figure A6-51). 
However, the PHREEQC analyses could not match groundwater F or dD data at the DFGP well. 
The inability to match the dD data could reflect differences in the ages of waters actually mixed 
to produce the DPGP water. The J-11 water could not be directly mixed with JF-3 because these 
two wells are kilometers apart. Instead, a water similar to J-11 could have been mixed with a 
water similar to JF-3 to produce the DFGP water. The actual waters mixed could have been 
different from J-11 or JF-3 in age. The inability to match the F- data may reflect analytical errors 
in the F- analyses or water/rock interactions not specified in the PHREEQC calculations (e.g., 
dissolution of fluorite (CaF2)). 
A6.3.8.2 Well 16S/49E-05acc 
The PHREEQC analyses investigated whether groundwater at the northernmost well in the 
FMW-S group (well 16S/49E-05acc) (Site 127) could be produced from groundwater in the 
southern part of the FMW-N group at well J-12 (Site 37). Groundwater from the JF well J-11 
(Site 67) was also included as a potential mixing member. The inclusion of well J-11 as a 
potential mixing member was motivated by the higher SO4
2 of groundwater in the FMW-S 
group compared to the FMW-N group and the very high SO4
2 at well J-11 (Figure A6-33). 
However, no PHREEQC analyses were identified that included well J-11 groundwater at well 
16S/49E-05acc. The 3 PHREEQC analyses for well 16S/49E-05acc were of the form: 
16S/49E-05acc = J-12 + calcite + plagioclase + K-feldspar + gypsum  Ca-clinoptilolite + biotite 
+ pyrite + O2 (g)  Fe(OH)3(a) 
Subsets of the phases indicated in the preceding reaction were identified in 3 reaction analyses 
by PHREEQC for this pair of wells. The PHREEQC analyses were able to match the d13C at 
well 16S/49E-05acc but not the d18O and dD values. The dD between the FMW-N and FMW-S 
groups is significantly different (Figure A6-41). The cause of this difference is probably climate 
change, which has resulted in the upgradient groundwater in the FMW-N group being of more 
recent origin compared to the downgradient groundwater in the FMW-S group (Figure A6-41). 
The groundwater in the FMW-S group is older and contains a greater percentage of cooler 
Pleistocene recharge, which in turn, has lighter dD. 
A6.3.8.3 GEXA Well 4 
The groundwater at GEXA well 4 (Site 68) was modeled as a mixture of the groundwater in 
lower Beatty Wash at well ER-OV-03c (Site 23) and local recharge from surface runoff. 
Recharge from surface runoff is likely because GEXA well 4 is located in a major drainage in 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-184 November 2004 
northwest Crater Flat (Figure A6-4). Because the chemical and isotopic characteristics of local 
recharge from surface runoff have not been measured in this area, the chemical and isotopic 
characteristics of the local recharge represented by groundwater from 29a#2 (Site 31) in 
Fortymile Canyon was used. The 9 models identified by PHREEQC were of the form: 
GEXA Well 4 = X1 ER-OV-03c + X2 recharge from runoff + calcite + dolomite + plagioclase + 
SiO2(a) + K-feldspar  smectite  Na-clinoptilolite + pyrite + O2 (g)  Fe(OH)3(a)  CaX2  
MgX2  KX + NaX 
where the fraction of well ER-OV-03c groundwater (X1) ranged from about 0.68 to 0.79 and the 
fraction of recharge from surface runoff (X2) ranged from about 0.21 to 0.32. Subsets of the 
phases indicated in the preceding reaction were identified in 9 reaction analyses by PHREEQC 
for the group of wells. Dolomite was considered a potentially reactive phase due to the presence 
of Paleozoic dolomites at Bare Mountain. The PHREEQC analyses successfully matched the 
d18O and dD of groundwater at GEXA well 4 in addition to the ion composition. 
A6.3.8.4 Borehole VH-1 
The groundwater at borehole VH-1 (site 69) was modeled as a potential mixture of groundwater 
from GEXA Well 4 (Site 68) and groundwater from Beatty Wash at well ER-OV-03c (Site 23), 
Coffer Ranch Windmill Well (CRWW) (Site 22), and ER-EC-07 (Site 24). These wells were 
chosen as potential mixing components because they are all upgradient from borehole VH-1. 
Furthermore, these upgradient wells spanned a considerable range in Cl, SO4
2, d18O, and dD 
(Section A6.3.4), which collectively bounded the values in groundwater at borehole VH-1. The 
6 analyses identified by PHREEQC were of the form: 
VH-1 = X1 ER-OV-03c + X2 CRWW + X3 ER-OV-07 + X4 GEXA well 4 + dolomite + 
plagioclase + SiO2(a) + K-feldspar  smectite  Na-clinoptilolite + pyrite + O2(g)  Fe(OH)3(a)  
CaX2  KX + NaX 
where X1 is the fraction of groundwater from well ER-OV-03c, X2 is the fraction of groundwater 
from the CRWW, X3 is the fraction of groundwater from well ER-OV-07, and X4 is the fraction 
of groundwater from GEXA well 4. Subsets of the phases indicated in the preceding reaction 
were identified in 6 reaction analyses by PHREEQC for this set of wells. Four of the six 
analyses were two component-mixing models involving roughly equal amounts of ER-OV-03c 
and CRWW groundwater. Of the two remaining analyses, one model was a three-component 
mixing model involving roughly equal amounts of ER-OV-03c (X1 = 0.34), CRWW (X2 = 0.29), 
and GEXA well 4 (X4 = 0.37) groundwater, and one model involved about 10 percent of 
groundwater from ER-EC-07 with subequal amounts of ER-OV-03c (X1 = 0.39) and CRWW (X2 
= 0.53) groundwater. The models collectively indicate that most of the groundwater originates 
from lower Beatty Wash, with at most, a small component from upper Beatty Wash at well EREC-
07. In light of the PHREEQC analyses for GEXA well 4 groundwater that indicate a 
component of local recharge from surface runoff, the groundwater at well VH-1 may also 
include a small component of local recharge from surface runoff in the northwest corner of 
Crater Flat. In addition to explaining the ion composition of groundwater at VH-1, the 
PHREEQC analyses accurately replicate the d18O and dD of groundwater at VH-1. However, 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-185 November 2004 
attempts to simultaneously model the relatively light d13C (8.5 per mil) of groundwater at 
borehole VH-1 were unsuccessful. 
A6.3.8.5 Well NC-EWDP-1S (Composite) 
Groundwater at well NC-EWDP-1S (composite) (Site 77) was evaluated as a potential mixture 
of groundwater at upgradient wells VH-1 (Site 69) and VH-2 (Site 70). These components were 
suggested by the hydraulic gradient and fault orientations (Figure A6.5-1) and by the fact that 
many chemical and isotopic species in groundwater at well NC-EWDP-1S (composite) are very 
similar in composition to the groundwater at borehole VH-2 (Section A6.3.4). The 9 models 
identified by PHREEQC were of the form: 
NC-EWDP-1S (composite) = X1 VH-1 + X2 VH-2 + dolomite  calcite + Plagioclase + SiO2(a) + 
K-feldspar  Na-clinoptilolite  smectite  KX + NaX 
where the fraction of well VH-1 groundwater (X1) ranged from about 0.14 to 0.16 and the 
fraction of groundwater from well VH-2 (X2) ranged from about 0.84 to 0.86. Subsets of the 
phases indicated in the preceding reaction were identified in the 9 reaction models by PHREEQC 
for group of wells. Note that in southwestern Crater Flat, the groundwater is saturated with 
calcite (Figure A6.3-34), so that calcite precipitation rather than dissolution is likely. In addition 
to reproducing the ion compositions, the PHREEQC analyses were also able to reproduce the 
d18O and dD compositions of groundwater at NC-EWDP-1S (composite) with a high degree of 
accuracy. These models indicate that groundwater at NC-EWDP-1S (composite) originates 
dominantly from groundwater at well VH-2. 
A6.3.8.6 Well NC-EWDP-9SX (Composite) 
Groundwater at well NC-EWDP-9SX (composite) (Site 81) was evaluated as a potential mixture 
of groundwater at upgradient wells VH-1 (Site 69) and VH-2 (Site 70). These components were 
suggested by the hydraulic gradient and fault orientations (Figure A6.5-1) and by the fact that 
many chemical and isotopic species in groundwater at well NC-EWDP-9SX (composite) are 
intermediate in composition between the groundwaters at boreholes VH-1 and VH-2 
(Section A6.3.7.1). The 3 models identified by PHREEQC were of the form: 
NC-EWDP-9SX (composite) = X1 VH-1 + X2 VH-2 + plagioclase + SiO2(a) + K-feldspar  Naclinoptilolite 
 smectite  CaX2  KX + NaX 
where the fraction of well VH-1 groundwater (X1) ranged from about 0.78 to 0.79 and the 
fraction of groundwater from well VH-2 (X2) ranged from about 0.21 and 0.22. Subsets of the 
phases indicated in the preceding reaction were identified in the 3 reaction models identified by 
PHREEQC for this group of wells. In addition to reproducing the ion compositions, the 
PHREEQC analyses were also able to reproduce the d18O and dD compositions of groundwater 
at NC-EWDP-9SX (composite) with a high degree of accuracy. These models are consistent 
with the interpretation that groundwater at NC-EWDP-9S originates dominantly from 
groundwater at well VH-1. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-186 November 2004 
A6.3.8.7 Well NC-EWDP-3D (Composite) 
Groundwater at well NC-EWDP-3D (composite) (Site 86) was evaluated as a potential mixture 
of groundwater at upgradient wells VH-1 (Site 69) and WT-10 (Site 42). These components 
were suggested by the hydraulic gradient and fault orientations (Figure A6.5-1) and by the fact 
that many chemical and isotopic species in groundwater at well NC-EWDP-3D (composite) are 
intermediate in composition between the groundwaters at boreholes VH-1 and WT-10 
(Section A6.3.4). The 1 model identified by PHREEQC was of the form: 
NC-EWDP-3D (composite) = X1 VH-1 + X2 WT-10 + calcite + plagioclase + SiO2(a) + Kfeldspar 
+ kaolinite  Na-clinoptilolite  MgX2 + NaX 
with the fraction of well VH-1 groundwater (X1) equal to 0.80 and the fraction of groundwater 
from well WT-10 (X2) equal to 0.20. In addition to reproducing the ion compositions, the 
PHREEQC models were also able to reproduce the d18O, dD, and d13C compositions of 
groundwater at NC-EWDP-3D (composite) with a high degree of accuracy. These models 
indicate that groundwater at NC-EWDP-3D originates dominantly from groundwater at well 
VH-1. 
A6.3.8.8 Well NC-EWDP-15P 
The groundwater at well NC-EWDP-15P (Site 90) was modeled as a potential mixture of 
groundwaters from upgradient wells VH-1 (Site 69) and WT-10 (Site 42). The 
carbonate-aquifer-like groundwater from borehole VH-2 (Site 70) was also considered as a 
potential component based on head gradients in southern Crater Flat and Yucca Mountain and on 
mixing trends that suggested a carbonate-aquifer component in the groundwater in this area (see 
Section A6.3.7.1). The 2 PHREEQC analyses found for well NC-EWDP-15P took the form: 
NC-EWDP-15P = X1 WT-10 + X2 VH-2 + X3 VH-1 + SiO2(a) + K-feldspar +gypsum  Naclinoptilolite 
 smectite 
where the fraction of well WT-10 groundwater (X1) was approximately 0.45 to 0.49, the fraction 
of carbonate aquifer groundwater from borehole VH-2 (X2) was 0.05 to 0.06, and the fraction of 
groundwater from well VH-1 (X3) was about 0.45 to 0.49. The 2 PHREEQC analyses were able 
to successfully match the d18O and dD at well NC-EWDP-15P with a high degree of accuracy. 
The d13C of groundwater at NC-EWDP-15P was not estimated by the inverse models because no 
groundwater d13C data were available from borehole VH-2. The PHREEQC analyses support 
the hypothesis that groundwater flows from eastern Crater Flat through wells in southern Yucca 
Mountain. 
A6.3.8.9 Borehole WT-3 
The PHREEQC models investigated whether groundwater at borehole WT-3 (Site 65) could 
have evolved from groundwater in northern Yucca Mountain at borehole WT-24 (Site 44). This 
possible flow path was suggested by fault orientations and the hydraulic gradient in the northern 
Yucca Mountain area, the high 234U/238U activity ratio at both boreholes, and the fact that 
groundwater at borehole WT-24 is the only location upgradient from borehole WT-3 with a 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-187 November 2004 
higher 14C activity. The reaction models for these wells assumed that calcite dissolved along the 
flow path had a d13C of 1.0  3 per mil because this is a common value measured in saturated 
zone calcite (Whelan et al., 1998, Figure 3. [DIRS 108865]). The reactions identified by 
PHREEQC for this flow path were of the general form: 
WT-3 = WT-24 + calcite + fluorite + SiO2(a) + K-feldspar + kaolinite  smectite  
Ca-clinoptilolite + biotite + O2(g)  Fe(OH)3(a)  CaX2  MgX2 
Subsets of the phases indicated in the preceding reaction were identified in 6 reaction models 
identified by PHREEQC for this pair of wells. The results of the reactions models confirm this 
as a plausible flow path. 
A6.3.8.10 Well NC-EWDP-19D and -19P 
Groundwater at well NC-EWDP-19D (Sites 92 and 9498) was sampled from several different 
zones in alluvium as well as from longer intervals spanning the depth of the alluvium or the 
entire well. The chemistry and isotopic compositions of these zones exhibited substantial 
differences in both chemical and isotopic compositions (see Section A6.3.3). Although cation, 
bicarbonate, and isotope compositions varied substantially among different zones, the 
groundwater Cl and SO4
2 compositions within almost all zones are uniformly low. The 
similarity of groundwater Cl and SO4
2 compositions in well NC-EWDP-19D and upgradient 
well WT-3 (Site 65) suggests a flow path between these two wells, in spite of the differences in 
other chemical and isotopic species. Groundwater at well WT-3 is also the only upgradient 
groundwater with 14C activity high enough to explain the high 14C activities of some zones in 
well NC-EWDP-19D. One group of models for well NC-EWDP-19D therefore attempts to 
explain the compositional difference between wells WT-3 and various zones within well 
NC-EWDP-19D as the result of water rock interactions along the flow path between the wells. 
The same set of reactions are applied to varying extents to explain the differences in 
compositions between various depth intervals in well NC-EWDP-19D: 
NC-EWDP-19D (various zones) = WT-3 + calcite + SiO2(a) + K-feldspar + kaolinite + 
plagioclase + gypsum  smectite  Ca-clinoptilolite + biotite + pyrite + O2 (g)  Fe(OH)3(a)  
CaX2  MgX2  KX + NaX 
Scatter plots (Figures A6-42 to A6-46) show that some groundwaters in the SCW group are 
similar to groundwater at well NC-EWDP-19D. Although slightly higher in Cl and SO4
2, 
groundwater in the SCW group is similar to groundwater at well NC-EWDP-19D with respect to 
cation compositions, DIC, and d13C. However, the groundwater 14C activities in the SCW area 
are far too low for this groundwater to be the source of groundwater at NC-EWDP-19D unless 
the SCW groundwater mixes with younger groundwater along its flow path. This younger water 
is assumed to be local recharge from Yucca Mountain itself, as represented by perched water 
from borehole SD-7. Some component of local recharge in southern Yucca Mountain is 
consistent with the hypothesis that much of the groundwater at Yucca Mountain is derived from 
local recharge (Section A6.3.6). The local recharge represented by perched water from SD-7 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-188 November 2004 
also has lower Cl and SO4
2 concentrations than the well NC-EWDP-19D, making it a suitable 
mixing end member. This group of models can be represented as: 
NC-EWDP-19D (various zones) = X1 WT-10 + X2 local recharge (SD-7 perched water) + calcite 
+ SiO2(a) + K-feldspar + kaolinite + plagioclase + gypsum  smectite  Ca-clinoptilolite + 
biotite + pyrite + O2(g)  Fe(OH)3(a)  CaX2  MgX2  KX + NaX 
where X1 is the fraction of groundwater from SCW well WT-10 (Site 42), X2 is the fraction of 
local recharge (as represented by perched water from borehole SD-7). Similar chemical 
processes but different sources are invoked in the two sets of PHREEQC models to explain the 
composition of groundwater within different zones in well NC-EWDP-19D. Both sets of models 
are able to explain the chemical compositions and d13C values of groundwater in various zones at 
well NC-EWDP-19D, but neither set of models adequately explains the extremely light d18O and 
dD compositions in some of these zones. 
The PHREEQC analyses for groundwater at well NC-EWDP-19P (Site 93) use the same set of 
reactions as for -19D but consider groundwater flow from well WT-3 and well JF-3 in the 
FMW-N group as possible sources of groundwater at well NC-EWDP-19P. The PHREEQC 
analyses results indicate that 80 to 100 percent of the shallow groundwater in well 
NC-EWDP-19P originates from the area of well JF-3. 
A6.3.9 Evaluation of Groundwater Velocities in the Yucca Mountain Region 
In this section, groundwater velocities are estimated along various flow-path segments using the 
14C activities of the groundwater along the flow path. The measured 14C activities at the 
upgradient well defining the segment are adjusted to account for decreases in the 14C activity that 
result from water-rock interactions the groundwater undergoes between wells, as identified by 
the PHREEQC mixing and chemical reaction models described in Section A6.3.8. This 
adjustment to the initial 14C activity at the upgradient well is necessary to distinguish between 
the decrease in 14C activity caused by water-rock interaction and the decrease in 14C activity due 
to transit time between the wells. After determining the transit time between wells, linear 
groundwater velocities are determined by dividing the distance between the wells by the transit 
time. 
The transit time between wells is calculated from the radioactive decay equation for 14C 
(Section A6.3.1.2.2). A variety of methods have been used to estimate the value of 14A0 to use 
with the radioactive decay law (Clark and Fritz 1997 [DIRS 105738], Chapter 8). One simple 
method that can be used to correct for the effects of calcite (or dolomite) dissolution in the case 
where the downgradient groundwater evolves from a single upgradient source is to compare the 
total DIC in the upgradient well (DICu) with the DIC of the downgradient groundwater (DICd) 
(Clark and Fritz 1997 [DIRS 105738], p. 209): 
qDIC = DICu 
DICd 
(Eq. 6-10) 
where qDIC represents the fraction of the DIC in the downgradient that originated from the 
upgradient well, with the remainder acquired from water-rock-gas interactions. Therefore, the 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-189 November 2004 
initial value of 14A0 is the product of qDIC and the measured 14C activity at the upgradient well 
(14Au): 
14A0 = 14Au  qDIC (Eq. 6-11) 
Several assumptions are made to simplify this calculation. The method assumes that after 
infiltration reaches the SZ and becomes recharge, the water is effectively isolated from further 
interaction with carbon dioxide gas in the unsaturated zone, so that any downgradient increases 
in the DIC of the groundwater are a result of interactions with carbon-bearing minerals. These 
minerals are assumed to be depleted in 14C, which is probably the case because most SZ calcite 
was formed either during a 10-million-year-old hydrothermal event or under unsaturated 
conditions at a time when the water table was lower than today (Whelan et al. 1998 
[DIRS 108865], p. 180). Thus, although the proportions of dissolved carbon-dioxide gas, 
bicarbonate, and carbonate may change with pH as the groundwater interacts with the rock, the 
total DIC is fixed unless the groundwater reacts with calcite. This method would not account for 
any interactions between groundwater and calcite once the groundwater had become saturated 
with calcite (Table A5-1, Assumption 8), nor would it account for the effects of groundwater 
mixing. This method was applied to obtain a preliminary estimate for the case that the 
upgradient groundwater was undersaturated with calcite and mixing was not considered an 
important process based on the PHREEQC inverse analyses. 
Additional simplifying assumptions in evaluating transport times based on 14C ages along flow 
paths include: groundwater flows along the straight-line distance between wells. This is a 
necessary, though likely inaccurate, assumption since the quantitative data for a particular 
nonlinear travel path are lacking. Using the straight-line distance yields the highest flow 
velocity. Also, the effects of matrix diffusion are not accounted for, though they are likely. 
Matrix diffusion may add older DIC to the groundwater. Corrections to account for this older 
component would also increase the calculated flow velocity. 
For flow path segments in which PHREEQC inverse analyses indicate the downgradient 
groundwater evolves from a single upgradient well, the value of 14AU is simply groundwater 14A 
at the upgradient well and the expression for qDIC is computed as follows: 
qDIC = (DICu)/(DICu + DICcarbonate) (Eq. 6-12) 
where DICu is the DIC at the upgradient well and DICcarbonate is the amount of carbon contributed 
by water-rock interactions involving carbonate rocks. The denominator in Equation 12 was 
expressed as DICu + DICcarbonate rather than simply as the measured value of DICd to allow for 
the possibility that the measured DIC concentrations were affected by CO2(g) de-gassing either 
during flow or during sampling. 
For flow path segments for which the PHREEQC inverse analyses identified mixing as an 
important control on the downgradient groundwater chemistry, the values of 14Au and qDIC were 
calculated as follows: 
14Au = (f1 14A1 DIC1 + f2 14A2 DIC2 +  + fi 14Ai DICi)/(f1 DIC1 + f2 DIC2 +  + fi DICi) 
(Eq. 6-13) 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-190 November 2004 
and 
qDIC = (f1 DIC1 + f2 DIC2 +  + fi DICi)/(f1 DIC1 + f2 DIC2 +  + fi DICi + DICcarbonate) 
(Eq. 6-14) 
where fi is the fraction of upgradient component i in the mixture. The equations do not consider 
the effects of CO2 degassing or dissolution, or calcite precipitation on 14C activity. This 
omission is an acceptable simplification because the fractionation factor for 14C is small (Clark 
and Fritz 1997 [DIRS 105738], inside front cover), and the 14C in the CO2 or calcite exiting the 
groundwater should leave the 14C in the groundwater relatively unchanged. Gas dissolution by 
the groundwater should not occur in most instances because the log PCO2 of the groundwater is 
higher than that of the overlying unsaturated zone (see Section A6.3.8). 
It is important to recognize that the hydrogeologic environment at Yucca Mountain represents a 
departure from the ideal circumstances under which 14C activities can be reliably used to 
calculate groundwater velocities. Ideally, the 14C method should be used where recharge is 
added at a known location and moves through a confined aquifer, isolated from the effects of 
groundwater mixing or downgradient additions of recharge. The degree of confinement of the 
aquifers at Yucca Mountain is not known, and mixing and downgradient additions of recharge 
are possible that could cause conditions to depart from the ideal circumstances. The PHREEQC 
analyses that have identified groundwater mixing as a process affecting groundwater 
compositions can, in theory, help to calculate the effects of groundwater mixing on 14C activities, 
as described in Equations 6-13 and 6-14. However, in the Yucca Mountain area, the calculation 
of groundwater velocities based on 14C activities is made more complicated by the possible 
presence of multiple, distributed recharge areas. If relatively young recharge were added along a 
flow path, the 14C activity of the mixed groundwater would be higher, and the calculated transit 
times shorter, than for the premixed groundwater without the downgradient recharge. 
Unfortunately, the chemical and isotopic characteristics of the recharge from various areas at 
Yucca Mountain may not be sufficiently distinct to identify separate sources of local recharge in 
the groundwater. 
Despite these nonideal conditions, groundwater velocities were calculated for several possible 
flow paths south of the repository in the Yucca Mountain area. The results of the calculations 
are described in the following subsections. These results should be viewed in light of the 
reservations noted above. 
A6.3.9.1 Flow-Path Segment from Well WT-3 to Well NC-EWDP-19D 
The PHREEQC inverse analyses (Section A6.3.8) indicate that groundwater sampled from 
various zones in well NC-EWDP-19D (Sites 92 and 9498) could have evolved from 
groundwater at well WT-3 (Site 65). Table A6-11 shows the transit times calculated by using 
the DIC of groundwater at well WT-3 and PHREEQC estimates of the carbon dissolved by this 
groundwater as it moves toward various zones at well NC-EWDP-19D (Equation 6-12). The 
third column of Table A6-11 refers to the transit time estimate made from the measured DIC at 
well WT-3 and that particular zone in well NC-EWDP-19D. The differences between the transit 
times based on the PHREEQC analyses results (Table A6-11, Column 2) and the transit times 
based on the measured differences in DIC concentrations (Table A6-11, Column 3) arise from 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-191 November 2004 
the fact that the PHREEQC analyses allow the DIC concentrations at each of the 2 wells to vary 
within 10 percent of their measured values, resulting in slightly different estimates of the amount 
of calcite dissolution along this flow path. These small differences in the estimates of calcite 
dissolution can cause transit times to vary from positive to negative and vice versa when the 
differences in 14C activity between the upgradient and downgradient wells are small, as in the 
models involving zones 1 and 2 of NC-EWDP-19D (sites 95 and 96). 
As Table A6-11 indicates, groundwater in the composite well and alluvial groundwaters require 
approximately 1,000 years to travel the approximately 15-km distance between wells WT-3 and 
NC-EWDP-19D. This transport time equates to linear groundwater velocities of approximately 
15-m/year. The groundwater in the deeper alluvial zones (Zones 3 and 4) requires approximately 
1,500 to 3,000 years and, thus, travels at a linear groundwater velocity of 5 to 10-m/year. In 
contrast, the transit times calculated for groundwater from shallow Zones 1 and 2 have transit 
times that range from 0 to about 350 years. Many of the calculated groundwater transit times 
were negative, indicating that the differences between 14C activities in groundwater at well WT-3 
and these zones in well NC-EWDP-19D were too small, and the uncertainty in DIC reactions 
estimated by PHREEQC too large, to adequately resolve the transit times. Using the upper 
transit time of 188 years, groundwater flow from well WT-3 to Zone 2 in well NC-EWDP-19D 
is about 80-m/year. Likewise, using the upper transit time of 535 years, groundwater flow from 
WT-3 to zone 1 of NC-EWDP-19D is about 28 m/year. These relatively high velocities may 
indicate that some of the shallow groundwater at well WT-3 moves along major faults like the 
Paintbrush Canyon fault, the effects of regionally convergent groundwater flow indicated by the 
hydraulic gradient (Figure A6.5-1), or they may simply reflect uncertainty in some assumptions 
implicit in this method, as discussed above in Section A6.3.9. 
Table A6-11. Calculated Groundwater Transit Times (in years) between Well WT-3 and Various Depth 
Zones in Well NC-EWDP-19D 
Zone in NC-EWDP-19D 
Mean transit time based on 
PHREEQC analyses (years)a 
Transit time based on qDIC = 
DICU/DICD (years) 
1 535  1 -926b 
2 -115  112b 188 
3 3110c 1601 
4 1684  2 1681 
alluvial zone 1065  2 1063 
Composite (combined alluvial and 
volcanic zones) 870  2 866 
DTN: LA0310EK831232.001 [DIRS 165995] (inverse analyses); Table A6-2 (14C data); Table A6-3 
(DIC concentrations). 
a Uncertainties are 1 standard deviation of the times estimated using the model results. 
b Negative transit times were calculated because of small differences in the 14C activities of the upgradient 
and downgradient wells and uncertainty in the DIC concentrations and PHREEQC reaction analyses. 
c No standard deviation was calculated because only 1 model for this zone was identified. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-192 November 2004 
A6.3.9.2 Flow Path Segment from Well WT-24 to Well WT-3 
The transit times calculated by using the DIC of groundwater at well WT-24 (Site 44) and 
PHREEQC estimates of the carbon dissolved by this groundwater as it moves toward well WT-3 
(site 65) averaged -499  147 years. The transit time estimate based on the measured differences 
in DIC of groundwater at wells WT-24 and WT-3 is 216 years. The differences in the estimates 
arise from the fact that the PHREEQC analyses allow an uncertainty of 10 percent in the DIC 
concentrations at each of the wells, which allows a slightly larger amount of calcite to be 
dissolved in the models (33 to 39 mg/L in the PHREEQC analyses versus 23 mg/L based on the 
measured DIC values). Using the estimate of transit time based on the measured DIC values and 
a linear distance between wells WT-24 and WT-3 of 10-km results in a linear groundwater 
velocity of 46-m/year. 
A6.3.10 Groundwater Flow Patterns Simulated with the Saturated Zone Flow Model 
The site-scale SZ flow model (Output DTN: LA0304TM831231.002), or simply, the SZ flow 
model, was used to simulate the movement of a conservative tracer through various features in 
the model. The location of these features and their numerical designations in the model are 
shown in Figure 6-5 and Table 6-17. The goal of these simulations was to provide an 
understanding of where groundwater at any location in the flow system may have originated and 
to what extent groundwaters originating from various locations may mix. These simulation 
results are then qualitatively evaluated in the context of the understanding gained from the 
analysis of the hydrochemical and isotopic data discussed in the previous sections. 
The simulations performed with FEHM used the advection-dispersion (trac) macro embedded in 
that code to simulate the steady-state distribution of a tracer originating from most boundary 
segments and from Yucca Mountain and Fortymile Wash recharge. In each simulation, an 
assigned longitudinal dispersivity of 10 m and a transverse dispersivity of 1 m were used. Small 
dispersivities were assumed to better observe the effects of heterogeneities on groundwater 
mixing and dilution. Nonetheless, as in most simulations that use the advection-dispersion 
equation, some numerical dispersion due to the mesh discretization may also have affected the 
tracer simulation results. For this reason, the simulation results are not analyzed quantitatively, 
and comparisons to the geochemical data are qualitative in nature. 
The flow-system behavior illustrated by these simulations is partly the result of the distributions 
of aquifers and confining units in the model (Figure A6-52). Where an aquifer exists along the 
boundary of the model, relatively large amounts of water enter the model along that boundary 
segment and the tracer originating from that segment dominates the character of the 
downgradient groundwater for a considerable distance. Conversely, where confining units are 
present along the boundary, groundwater inflow is small, and the tracer originating from that 
segment is readily diluted by the relatively larger amounts of untraced groundwater entering the 
model along the neighboring boundary segments. 
Two simulations were done for each boundary segment considered. The first simulation for each 
segment examined the steady-state distribution of inflow along the pre-Tertiary rocks contained 
within that boundary segment. These pre-Tertiary rocks include the granitic rocks, the Lower 
Clastic Confining Unit, the Lower Carbonate Aquifer, the Upper Clastic Confining unit, the 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-193 November 2004 
Lower Carbonate Aquifer Thrust, and the Upper Carbonate Aquifer Thrust. The Tertiary rocks 
(and sediment) include the remainder of the model units shown on Figure A6-52. The Prow Pass 
tuff, the Bullfrog tuff, and the Tram tuff, although not explicitly identified as aquifers in 
Figure A6-52, comprise the Lower Volcanic Aquifer of Luckey et al. (1996 [DIRS 100465], 
Figure 7). 
-2000 
-1000
0 
1000 
z 
535000 
540000 
545000 
550000 
555000 
560000 
x 
4.05E+06
4.06E+06
4.07E+06
4.08E+06
4.09E+06 
y 
Y 
X 
Z 
20.5 
19.5 
18.5 
17.5 
16.5 
15.5 
14.5 
13.5 
12.5 
11.5 
10.5 
9.5 
8.5 
7.5 
6.5 
5.5 
4.5 
3.5 
2.5 
1.5 
Saturated-zone hydrostratigraphic units 
Granite 
L. Clastic Conf. Unit 
L. Carbonate Aquifer 
U. Clastic Conf. Unit 
L Carb. Aquif. Thrust 
U. Carbonate Aquifer 
Valley Fill (undiff.) 
Older Volc. Conf. Unit 
Older Volc. Aquifer 
L. Volc. Conf. Unit 
Tram Tuff 
Bullfrog Tuff 
Prow Pass Tuff 
U. Volc. Conf. Unit 
U. Volcanic Aquifer 
Lava Flow Aquifer 
Limestone Aquifer 
Not Used 
Valley-Fill Aquifer 
Legend 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. X =UTM-Easting and Y =UTM-Northing. 
Figure A6-52. Geologic Units Defined in the Saturated Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-194 November 2004 
The first simulation result presented here shows the steady-state distribution of Yucca Mountain 
recharge in the model (Figure A6-53). Also shown in the figure are the locations of the 
boreholes that provided head data used in the calibration of the SZ flow model. Some key 
boreholes that figured prominently in the earlier discussions of the hydrochemistry are labeled in 
this and subsequent figures. The boreholes extend from ground surface (not shown) through the 
water table, which in this case, coincides with the top of the model. The length of the boreholes 
shown in these figures thus approximates the thickness of the UZ at that location. 
-2000 
-1000
0 
1000
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of YuccaMountain recharge 
GexaWell 4 G-2 
29a#2 
J-11 
TW-5 
-5S -1X -2D 
-1D
-9SX 
-3D 
WT-10 
WT-11 J-13 
JF-3 
VH-1 
WT-3 
Cind-R 
-Lite 
percent 
Yucca 
Mountain 
recharge 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. X =UTM-Easting and Y =UTM-Northing. 
Figure A6-53. Steady-State Distribution of the Percentage of Yucca Mountain Recharge in Downgradient 
Groundwater Calculated Using the Saturated Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-195 November 2004 
The longest boreholes are located along Yucca Crest where the unsaturated zone thickness can 
reach 750 m. 
The Yucca Mountain recharge entering the model was tagged with a concentration of 100 units, 
whereas all other water entering the model was given a tracer concentration of 0 units. The 
percentage of Yucca Mountain recharge at any location in the model is therefore equivalent to 
the tracer concentration at that location. The simulation results indicate that Yucca Mountain 
recharge is substantially diluted by groundwater flowing from adjacent parts of the flow system 
by the time it passes the Dune Wash area near well WT-3 (Site 65). The percentage of Yucca 
Mountain recharge in the groundwater is less than 10 percent near well NC-EWDP-2D (Site 91) 
along U.S. Highway 95. The downgradient decrease in tracer concentrations associated with 
Yucca Mountain recharge cannot be explained by spreading of the plume due to numerical 
dispersion because, in this case, the plume tends to become narrower and more focused in the 
downgradient direction. A more likely explanation is that as Yucca Mountain recharge moves 
downgradient, it is mixed and diluted by groundwater moving from more active parts of the flow 
system. These results are consistent with observed hydrochemical patterns and help to explain 
the difficulty in identifying Yucca Mountain recharge in groundwater near and south of 
U.S. Highway 95. 
The flow entering along the northern boundary of the model (zone 61) in northwest Crater Flat is 
shown in Figures A6-54 to A6-56. The flow through the pre-Tertiary rocks is predicted to 
emerge into the shallow part of the flow system in several points of the model, including the 
central part of Crater Flat near borehole VH-1 (Site 69) and the southern part of Crater Flat near 
well NC-EWDP-3D (Site 86) and the NC-EWDP-15P well (Site 90). The groundwater at 
borehole VH-2 (Site 70) in central Crater Flat does appear to have many of the characteristics of 
groundwater from the carbonate aquifer, and groundwater at well NC-EWDP-3D (Site 86) and 
the NC-EWDP-15P well (Site 90) were analyzed with the PHREEQC code to be partially 
derived from the carbonate aquifer, in agreement with these results. The deep groundwater 
flowing through Crater Flat is apparently forced both upward and to the east by a buried ridge 
formed by the low-permeability Lower Clastic Confining unit (compare Figures A6-52 and 
A6-55). The groundwater entering Crater Flat through the undifferentiated Valley Fill in 
zone 61 dominates the shallow flow system in most of Crater Flat, except for the westernmost 
part of Crater Flat where the groundwater enters from the western boundary along Bare 
Mountain. Although most of the groundwater entering the undifferentiated Valley Fill in 
northwest Crater Flat flows southward from borehole VH-1 (Site 69) to wells NC-EWDP-9SX 
(Sites 8185) and NC-EWDP-3D (Site 86), as analyzed with the PHREEQC calculations 
(Sections A6.3.8.6 and A6.3.8.7), a part of this groundwater flows southeastward past well 
WT-10 (Site 42) and into southern Yucca Mountain to become a component of the groundwater 
near the NC-EWDP-15P well (Site 90) and NC-EWDP-2D (Site 91). PHREEQC calculations 
for these well NC-EWDP-15P and for nearby well NC-EWDP-19D indicated that groundwater 
from well WT-10 (Site 42) could constitute a significant fraction of the groundwater at these 
wells (Sections A6.3.8.8 and A6.3.8.10). 
Because of the very low permeability of the pre-Tertiary rocks near Zone 62 at Timber 
Mountain, very little groundwater enters the model from this area and tracer concentrations 
indicate that inflow from this area exerts little influence on the downgradient water chemistry 
(figure not shown). The Tertiary rocks from Zone 62 include the relatively permeable upper 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-196 November 2004 
volcanic aquifer, which permits a considerably greater amount of groundwater to enter the model 
than the pre-Tertiary rocks in this zone. The steady-state distribution of tracer concentrations 
(Figure A6-57) indicates that groundwater entering through the Tertiary rocks of Zone 62 flows 
southward through Yucca Mountain and forms a component of the groundwater throughout the 
Yucca Mountain area, including southeastern Crater Flat at wells WT-10 (Site 42), 
NC-EWDP-3D (Site 86), the Cind-R-Lite well (Site 89), and wells NC-EWDP-2D (Site 91) and 
NC-EWDP-19D (Sites 92 and 9498) in southern Yucca Mountain near Fortymile Wash. The 
d13C of shallow groundwater in the northernmost part of Yucca Mountain is too light for that 
groundwater to have originated from groundwater directly to the north at well ER-EC-07 
(Site 24) in Beatty Wash. However, the increase in groundwater d13C southward at Yucca 
Mountain is consistent with an increasing component of groundwater from the area of well 
ER-EC-07 (Site 24) present in the Yucca Mountain groundwater. 
-2000 
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0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through the pre-Tertiary 
units of zone 61 (NW Crater Flat) 
Gexa Well 4 G-2 
29a#2 
VH-1 
J-11 
TW-5 
J-13 
JF-3 
WT-3 
WT-10 
WT-11 
-5S -1X -2D 
-1D 
-9SX 
-3D
Cind-R 
-Lite 
percent 
zone 61 
inflow 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. X =UTM-Easting and Y =UTM-Northing. 
Figure A6-54. Map View of Steady-State Distribution of the Percentage of Inflow through the Pre-Tertiary 
Units of Northwest Crater Flat Groundwater Calculated Using the Saturated Zone Flow 
Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-197 November 2004 
-2000 
-1000
0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through the pre-Tertiary 
units of zone 61 (NW Crater Flat) 
percent 
zone 61 
inflow 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. X =UTM-Easting and Y =UTM-Northing. 
Figure A6-55. Cross Sectional View of Steady-State Distribution of the Percentage of Inflow through the 
Pre-Tertiary Units of Northwest Crater Flat Groundwater Calculated Using the Saturated 
Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-198 November 2004 
-2000 
-1000
0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through Tertiary units 
of zone 61 (NW Crater Flat) 
Gexa Well 4 G-2 
29a#2 
J-11 
TW-5 
-5S
JF-3
J-13 WT-3 
VH-1 
WT-10 
WT-11 -1D 
-9SX 
-3D
Cind-R 
-Lite 
-2D -1X 
percent 
zone 61 
inflow 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. X =UTM-Easting and Y =UTM-Northing. 
Figure A6-56. Steady-State Distribution of the Percentage of Inflow through the Tertiary Units of 
Northwest Crater Flat Groundwater Calculated Using the Saturated Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-199 November 2004 
-2000 
-1000
0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through Tertiary 
units of zone 62 (Timber Mountain) 
percent 
zone 62 
inflow 
Gexa Well 4 
VH-1 
G-2 
29a#2 
J-11 
TW-5 
-5S -1X -2D 
WT-10 
WT-11 
J-13 
JF-3 
WT-3 -1D 
-9SX 
-3D
Cind-R 
-Lite 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. X =UTM-Easting and Y =UTM-Northing. 
Figure A6-57. Steady-State Distribution of the Percentage of Shallow Timber Mountain Area 
Groundwater through the Tertiary Units Calculated Using the Saturated Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-200 November 2004 
Groundwater entering the model domain from the pre-Tertiary rocks of Zone 63 near Fortymile 
Canyon follows a sinuous pathway through the Fortymile Wash area and western Jackass Flats 
as it moves southward through the model (Figures A6-58 and A6-59). The sinuous movement of 
this tracer plume in the model may be related to the deflection of groundwater eastward around 
the buried ridge of the Lower Clastic Confining unit in the southwestern part of the model 
(Figure A6-52) and, later, by the large amount of inflow from Zone 81 in the southeast part of 
the model (see below). Groundwater from the pre-Tertiary rocks of Zone 63 is predicted by the 
SZ flow model to be a small component of the shallow groundwater at borehole JF-3 (Site 37) 
and other Fortymile Wash area boreholes in the northern Amargosa Desert and in the Amargosa 
Valley area. The groundwater from the pre-Tertiary rocks of Zone 63 could be the component of 
groundwater from western Jackass Flats predicted from an analysis of sulfur isotopes to be 
present in minor amounts in some LW and FMW-E groundwaters (Figure A6-51). 
The steady-state distribution of groundwater entering the Fortymile Canyon area of the model 
through the Tertiary rocks of Zone 63 indicates that this groundwater is diluted by groundwater 
from other areas, including Yucca Mountain (Figure A6-60) by the time it has reached well 
J-13 (Site 35) in Fortymile Wash. The shallow groundwater entering Zone 63 again becomes a 
small component of the groundwater southward along Fortymile Wash near JF-3 (Site 37) and in 
southern Yucca Mountain near well NC-EWDP-2D (Site 91), but does not persist as an 
identifiable part of the groundwater in the FMW-S area wells. Dilution of the shallow inflow 
from Zone 63 by downgradient recharge along Fortymile Wash is not a plausible explanation for 
the dilution of the Zone 63 in flow, given the small amount of Fortymile Wash recharge present 
in the model. The geochemical and isotopic data from the FMW-N and FMW-S wells indicate a 
much more significant component of inflow from Zone 63, and perhaps of recharge along the 
wash, than is indicated by the SZ flow model. 
Like groundwater from the pre-Tertiary units of Zone 63, the groundwater entering the northern 
boundary through the pre-Tertiary rocks of Zone 64 beneath Shoshone Mountain follows a 
sinuous trajectory through western Jackass Flats and emerges into the shallow flow system in the 
vicinity of well NC-EWDP-5S (Site 154) of the Amargosa Valley area (figure not shown). Some 
of the groundwater entering the model through Zone 64 leaves the model along its eastern 
boundary. The model results suggest that the deep groundwater from Zone 64 could also be the 
component of groundwater from western Jackass Flats identified from d34S analysis to be present 
in some of the LW and FMW-E area wells. The Tertiary rocks of Zone 64 are comprised of 
confining units (Figure A6-52) and virtually no groundwater enters the model through these 
rocks. 
The groundwater in the southeast corner of the model near the Skeleton Hills area is dominated 
by inflow from pre-Tertiary rocks of Zone 81 (Figure A6-61). The model results are consistent 
with the geochemical and isotopic data from this area, which suggest that the groundwaters near 
the Gravity fault, and as far west as NC-EWDP-5S (Site 154) and some LW- and FMW-E area 
wells, contain a component of groundwater from the carbonate aquifer leaking into the alluvium 
across the Gravity fault. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-201 November 2004 
-2000 
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1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through the pre- 
Tertiary units of zone 63 (Fortymile Canyon) 
percent 
zone 63 
inflow 
Gexa Well 4 
29a#2 
J-11 
TW-5 
G-2 
VH-1 
-1D 
-9SX
-3D -2D -1X -5S 
WT-10 
WT-11 
J-13 
JF-3 
WT-3 
Cind-R 
-Lite 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. 
Figure A6-58. Map View of Steady-State Distribution of the Percentage of Shallow Upper Fortymile 
Wash Area Groundwater through the Pre-Tertiary Units Calculated Using the Saturated 
Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-202 November 2004 
-2000 
-1000
0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through the pre- 
Tertiary units of zone 63 (Fortymile Canyon) 
percent 
zone 63 
inflow 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. 
Figure A6-59. Cross Sectional View of Steady-State Distribution of the Percentage of Shallow Upper 
Fortymile Wash Area Groundwater through the Pre-Tertiary Units Calculated Using the 
Saturated Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-203 November 2004 
-2000 
-1000
0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0 
Steady-state distribution of inflow through Tertiary 
units along zone 63 (Fortymile Canyon) 
percent 
zone 63 
inflow 
Gexa Well 4 
29a#2 
J-11 
VH-1 
G-2 
TW-5 
-5S -1X 
J-13 
JF-3 
WT-3 
WT-10 
WT-11 -1D 
-9SX 
-3D
Cind-R 
-Lite
-2D 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. 
Figure A6-60. Steady-State Distribution of the Percentage of Shallow Upper Fortymile Wash Area 
Groundwater through the Tertiary Units Calculated Using the Saturated Zone Flow Model 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-204 November 2004 
-2000 
-1000
0 
1000 
z 
535000 540000 545000 550000 555000 560000 
x 
4.05E+06 
4.06E+06 
4.07E+06 
4.08E+06 
4.09E+06 
y 
Y 
X 
Z 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 
0
Steady-state distribution of inflow through pre- 
Tertiary units of zone 81 (Skeleton Hills area) 
percent 
zone 81 
inflow 
Gexa Well 4 
29a#2 
G-2 
VH-1 
J-11 
J-13 
JF-3
TW-5 
WT-3 
WT-10 
WT-11 
-5S -1X -2D 
-1D 
-9SX 
-3D
Cind-R 
-Lite 
Output DTN: LA0304TM831231.002. 
DTN: LA0309EK831231.001 [DIRS 171887]. 
NOTES: The X and Y coordinates are Universal Trans-Mercator Projection (UTM) coordinates in meters. The 
Z coordinate is elevation relative to sea level in meters. 
Figure A6-61. Steady-State Distribution of the Percentage of Pre-Tertiary Rocks of the Skeleton Hills 
Area Groundwater Calculated Using the Saturated Zone Flow Model 
In summary, the flow patterns and mixing relations identified with the SZ flow model are similar 
in many ways to the flow patterns and mixing relations inferred from the hydrochemical and 
isotopic data for the area. Of particular importance are the simulations of movement of recharge 
from the Yucca Mountain area. These simulations indicate that groundwater from Yucca 
Mountain may not be easily identifiable in groundwaters south of Yucca Mountain because of 
dilution by groundwater from other, more active parts of the flow system. The SZ flow model 
appears to underestimate the quantity of inflow from the Fortymile Canyon area through the 
Tertiary units. This conclusion is based on the observation that groundwater along Fortymile 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-205 November 2004 
Wash through Jackass Flats and the Amargosa Desert is chemically and isotopically unique 
compared to the surrounding groundwaters, but the tracer simulations indicate that groundwater 
inflow from Fortymile Canyon or from downgradient recharge along the wash is present only in 
dilute amounts along Fortymile Wash. Some of the discrepancy between the simulations and the 
data for the Fortymile Wash area may be due to recharge of some or most of this chemically 
distinct groundwater during wetter climate periods. 
A6.3.11 Regional Flow Paths Inferred from Hydrochemical Data 
Groundwater flow paths and mixing zones are identified on the basis of the preceding 
discussions of measured and calculated geochemical and isotopic parameters. The hydraulic 
gradient shown on the potentiometric surface map (Figure A6-3) is used to constrain flow 
directions only insofar as groundwater cannot flow from areas of lower hydraulic head to areas 
of higher hydraulic head. Chemical and isotopic composition of groundwater were then used to 
locate flow pathways in the context of the hydraulic gradient and considering the possibility that 
flow paths can be oblique to the potentiometric gradient because of anisotropy in permeability. 
The analysis of flow paths that follows assumes that Cl and SO4
2 values are conservative and 
that changes to these are due to mixing along flow paths. This same assumption holds for 
isotopes of hydrogen and oxygen; however, because recharge waters have almost certainly 
changed over time, it is to be expected that isotopic variability in these constituents will occur in 
groundwaters of different ages (Benson and Klieforth 1989 [DIRS 104370], Figure 11; 
Winograd et al. 1992 [DIRS 100094], Figure 2). In spite of the potential reactive nature of 
Na and Ca, the contrast in concentrations between some areas is great enough that meaningful 
inferences about flow directions can be made. 
Flow paths can be traced using conservative constituents 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 lines of 
evidence were used to construct the flow paths inferred in this section. This evidence includes 
the areal distribution of chemical and isotopic species, sources of recharge, groundwater ages 
and evaluation of mixing/groundwater evolution through scatterplots, and inverse mixing and 
reaction models as presented in the previous sections. 
Flow path 1 (Figure A6-62) traces the movement of groundwater southeastward from Oasis 
Valley (OV/NWA group) through the Amargosa Desert along the axis of the Amargosa River 
(AR and AR/FMW groups) to its confluence with Fortymile Wash (FMW-S group). This flow 
path is identified from areal plots of chloride (Figure A6-15) and scatterplots of SO4
2 versus 
Cl- (Figure A6-50) that support this flow path. It is inferred from Figure A6-50 that the more 
dilute groundwater from the Oasis Valley area (OV/NWA group) became concentrated by 
evapotranspiration (ET) as it moves from the Oasis Valley area into the northwestern Amargosa 
Desert toward sites 1517. This inference is based on the common trend of the OV/NWA and 
AR groups in Figure A6-50, which indicates that the composition of the AR group can be 
derived by concentrating groundwater from the OV/NWA group through evapotranspiration 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-206 November 2004 
downgradient from the Oasis Valley sample locations. Data contained in White (1979 
[DIRS 101165], Table 2, sample sites 28 and 29) corroborate this interpretation. These data 
show that groundwater exiting Oasis Valley through Beatty Narrows into the NW Amargosa 
Desert has a Cl concentration of between 76.9 and 100.0 mg/L and SO4
2 concentrations of 
between 183.5 and 249.8 mg/L. The more dilute solute concentration of these two samples is 
nearly identical to that from Sites 1517. The data in Figure A6-50 also indicate that 
groundwater in the CF-SW group has a much lower Cl- concentration than groundwater in the 
AR group, making it unlikely that groundwater from the CF-SW wells is a major component of 
groundwater in the AR and FMW-W wells. Groundwater along flow path 1 becomes more 
dilute in the AR/FMW wells as it becomes increasingly mixed with FMS-S group groundwater 
near Fortymile Wash (see below). Northwest of this mixing zone, high groundwater 
14C activities (Figure A6-28) and variable dD (Figure A6-24) and d18O (Figure A6-25) 
compositions at the AR wells indicate the presence of relatively young recharge in the 
groundwater due to runoff or irrigation in the area. 
Flow path 2 (Figure A6-62) traces the movement of groundwater from the Fortymile Canyon 
area southward along the axis of Fortymile Wash into the Amargosa Desert. This flow pathway 
is drawn on the basis of similar anion and cation concentrations along the flow line and 
dissimilarities compared to regions to the east and west (see, for example, Figures A6-15, A6-16, 
and A6-22). Groundwater along the northern part of this flow path (FMW-N groups samples) is 
distinguished from groundwater at Yucca Mountain by dD and d18O compositions that are 
heavier and/or more offset from the global meteoric water line (dD = 8 d18O + 10) than the 
groundwater found under Yucca Mountain (Figure A6-48). It is inferred that the groundwater 
found along the FMW-S wells in the Amargosa Desert is derived, in part, from groundwater flow 
from the FMW-N wells, based on the similarly dilute SO4
2 (Figure A6-16) and 
Cl- (Figure A6-15) compositions of these groundwaters. Differences in the dD compositions of 
the FMW-N and FMW-S groundwaters (Figure A6-24) are attributed to the effects of changing 
climatic conditions on the dD composition of recharge (see Section A6.3.6.6.1). Groundwater 
flow from the FMW-N area wells southward into the Amargosa Desert along the axis of the 
wash is also compatible with expected and observed chemical evolution trends between the two 
areas, such as downgradient increases in pH (Figure A6-14), calcite saturation indices 
(Figure A6-37), and HCO3
 (Figure A6-17) and SiO2 (Figure A6-1) concentrations. Some part 
of the groundwater along Fortymile Wash may also be derived by recharge from overland flow, 
based on the observation that 14C activities do not decrease systematically southward in either the 
northern or southern segments of the wash (Figure A6-28). Groundwater flow from the eastern 
and western parts of the Amargosa Desert toward Fortymile Wash is relatively minor, however, 
based on the much higher solute contents (Figures A6-15 to A6-17, and A6-34) and distinct 
isotopic compositions (Figures A6-26 and A6-27) of groundwaters adjacent to the FMW-S area 
wells. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-207 November 2004 
Flow path 3 (Figure A6-62) traces the movement of groundwater from Jackass Flats in the 
vicinity of well J-11 (Site 67) as it moves along the western edge of the Amargosa Valley (LW) 
area wells and arcs southward through the FMW-E area wells. The identification of groundwater 
from Jackass Flats in this mixture of groundwaters is possible because the high SO4
2 
and low 
d34S characteristics of groundwater from well J-11 distinguish it from the high SO4
2 and high 
d34S groundwater characteristic of the Gravity fault (GF group) and the low SO4
2 and low d34S 
groundwater of the Fortymile Wash area (FMW-S group) on scatterplots of d34S versus 1/SO4
2 
concentration (Figure A6-51). A source for this high SO4
2 groundwater from Jackass Flats 
rather than the Gravity fault area is also indicated by the similarly light d13C of groundwater 
along this flow path (Figure A6-27). 
Flow path 4 (Figure A6-62) traces the movement of groundwater from the lower Beatty Wash 
area (southern TM group samples) into northwestern Crater Flat. This groundwater flows 
predominantly southward in Crater Flat through Sites 69 (borehole VH-1) and Site 86 
(NC-EWDP-3D). The chemistry and isotopic composition of this groundwater appears to be a 
mixture of subequal amounts of groundwater from Sites 22 and 23 in lower Beatty Wash, with 
much smaller amounts of recharge from local runoff in Crater Flat or groundwater flow from 
Site 24 (Section A6.3.8.4). Dashed lines are used to illustrate these relationships on 
Figure A6-62. Groundwater from Site 68 (GEXA Well 4), which may be groundwater from 
Site 23 modified by recharge from surface runoff (Section A6.3.8.3), also contributes 
groundwater to this flow path. Scatterplots and PHREEQC inverse models (Sections A6.3.8.3 
and A6.3.8.4) show that a mixture of groundwater from Sites 22 and 23 is required to account for 
both the relatively low Cl and the light d18O and dD activity ratios characteristic of this flow 
path, whereas small amounts of recharge from local runoff or flow from Site 24 are needed to 
decrease the d13C of the lower Beatty Wash groundwater. 
Most groundwater at Timber Mountain north of Yucca Mountain (TM group) is characterized by 
d13C values that are too heavy (6 to 0 per mil) and 14C values that are too low for it to be a 
major source of groundwater at Yucca Mountain (Figure A6-45). The absence of significant 
amounts of Timber Mountain groundwater beneath Yucca Mountain is also indicated by the 
extremely low d87Sr and high Sr2+ concentration of the Timber Mountain groundwater compared 
to Yucca Mountain (Figure A6-32 and A6-31). The extremely light d13C (Figures A6-27 and 
A6-45) and high d87Sr (Figure A6-32) of groundwater in northern Yucca Mountain (YM-CR 
group) compared to Timber Mountain (TM group) groundwater indicates that groundwater from 
the Timber Mountain/Beatty Wash area does not flow south through northern Yucca Mountain. 
One well in upper Beatty Wash (Site 24 - ER-EC-07) has a high 14C activity (Figure A-28), and 
d13C (Figure A6-27) and d87Sr values (Figure A6-32) similar to those of groundwaters in the 
Solitario Canyon Wash area (SCW group) and to groundwater south of Drill Hole Wash at 
Yucca Mountain. Based on Figure A6-45, some groundwater from the area of well ER-EC-07 in 
upper Beatty Wash could be present in Yucca Mountain groundwater south of Drill Hole Wash 
(YM-C, YM-SE and YM-S groups) and along Solitario Canyon Wash (SCW group) if sorption 
on rock removed most of the Sr2+ from the Beatty Wash area along its flow path. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-208 November 2004 
Flow path 5 (Figure A6-62) traces groundwater with a distinct chemical composition that 
comprises the SW Crater Flat (CF-SW) Group. Groundwater from site 70 (borehole VH-2) 
is chemically and isotopically distinct from groundwater that characterizes flow path 4, with 
higher concentrations of many major ions (Figures A6-15 to A6-17) (but lower 
concentrations of F (Figure A6-18) and SiO2 (Figure A6-19)) and relatively high d18O 
(Figure A6-25) and dD (Figures A6-24 and A6-49) values. The d18O and dD of groundwater 
from borehole VH-2 is similar to groundwater from Species Spring (Rose et al. 1997 
[DIRS 144725]), a perched spring at Bare Mountain, suggesting that groundwater at borehole 
VH-2 and other CF-SW group wells are derived principally from local recharge and runoff 
from Bare Mountain. Dashed east and southeast-oriented lines schematically illustrate this 
flow (Figure A6-62). Groundwater in Oasis valley has some of the lightest groundwater dD 
and d18O values in the Yucca Mountain area (Figures A6-24 and A6-25), eliminating flow 
from Oasis Valley under Bare Mountain as a possible source of groundwater in southwest 
Crater Flat. The similar chemical and isotopic characteristics between groundwater from 
borehole VH-2 and other southwest Crater Flat boreholes (Section A6.3.4) and PHREEQC 
models of Sites 77 and 81 (Sections A6.3.8.5 and A6.3.8.6) indicate a dominantly 
north-south flow along this flow path as far south as these sites. Importantly, the chemically 
distinct groundwater along this flow pathway is not observed in boreholes to the south in the 
Amargosa Desert (AR and FMW-S groups) (for example, see Figure A6-50). Mixing 
relationships discussed in connection with Figure A6-49, and PHREEQC models of Sites 86 
and 90 (Sections A6.3.8.7 and A6.3.8.8), suggest that this groundwater likely flows to the 
east and southeast and mixes with wells from the YM-S group (Figure A6-49). 
Flow path 6 (Figure A6-62) traces the movement of groundwater from Site 42 (well WT-10) 
southward toward Sites 89 (Cind-R-Lite well) and 90 (well NC-EWDP-15P). This flow path is 
identified from PHREEQC models that indicate that groundwater from well NC-EWDP-15P is 
formed from subequal amounts of groundwater from Sites 69 (well VH-1) and 42 (well WT-10), 
with a minor component (5 percent) of groundwater like that from Site 70 (well VH-2) (see 
Section A6.3.8.8). Mixing trends indicated by plots of Cl versus dD (Figure A6-49) also suggest 
leakage from Crater Flat toward the YM-S group in southern Yucca Mountain. Although the 
predominant direction of flow from the Solitario Canyon (SCW group) area is southward along 
the Solitario Canyon fault, evidence for the leakage of small amounts of groundwater eastward 
across the fault is also provided by similarities in the ion concentrations and isotopic values of 
groundwaters in the SCW and YM-CR area wells (Section A6.3.6.3, Figures A6-42 to A6-46). 
This chemical and isotopic similarity indicates that groundwater as far east as borehole 
NC-EWDP-19D may have some component of groundwater from the Solitario Canyon Wash 
area. The short southeast-oriented dashed lines from Solitario Canyon group wells schematically 
illustrate this leakage. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-209 November 2004 
DTN: LA0308RR831233.001 [DIRS 171890]. 
NOTES: This figure has color-coded data points and should not be read in a black and white version. Solid lines 
indicate a relatively high degree of confidence in the interpretations; dashed flow paths indicate relatively 
less confidence. Base map shows borehole designators and inserts; for reference see Figure A6-5 and 
Table A4-3. UTM-X =UTM-Easting and UTM-Y =UTM-Northing. UTM=Universal Transverse Mercator. 
Figure A6-62. Regional Flow Paths Inferred from Hydrochemical and Isotopic Data 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-210 November 2004 
Flow path 7 (Figure A6-62) traces the movement of groundwater from northern Yucca Mountain 
southeastward toward YM-SE wells in the Dune Wash area and then southwestward along the 
western edge of Fortymile Wash. The upper segment of this flow path is motivated by the high 
groundwater 234U/238U activity ratios found in the northern Yucca Mountain and Dune Wash 
areas (Figure A6-47). High 234U/238U activity ratios (greater than 7) typify both perched water 
and groundwater along and north of Drill Hole Wash but not groundwater along Yucca Crest at 
borehole SD-6 (Site 50) or perched water at borehole SD-7. Based on the conceptual model for 
the evolution of 234U/238U activity ratios described in Section A6.3.6.2, dissolution of thick vitric 
tuffs that underlie the Topopah Spring welded tuff along Yucca Crest south of Drill Hole Wash 
would be expected to decrease the 234U/238U activity ratios of deep unsaturated zone percolation 
south of the Wash. High 234U/238U activity ratios are expected only where these vitric tuffs are 
absent, as in northern Yucca Mountain. Results of a PHREEQC analysis of the evolution of 
groundwater between site 44 (well WT-24) in northern Yucca Mountain and Site 65 (well WT-3) 
in the Dune Wash area are consistent with this segment of flow path 7 (Section A6.3.8.9). The 
southern segment of flow path 7 is based on PHREEQC analyses of groundwater evolution 
between well WT-3 and various depth intervals of well NC-EWDP-19D (Sites 92 and 94 to 98) 
(Section A6.3.8.10). Groundwater at well NC-EWDP-19D has low Cl (Figure A6-15) and 
SO4
2- (Figure A6-16) concentrations that are characteristic of groundwater at well WT-3. The 
light d18O and dD values eliminate Fortymile Wash as a possible source of the dilute 
groundwater at well NC-EWDP-19D (Figures A6-24, A6-25, A6-44 and A6-48). An alternative 
set of PHREEQC analyses was developed that interprets the groundwater at NC-EWDP-19D to 
be a result of the mixing of groundwater from well WT-10 and local southern Yucca Mountain 
recharge, as represented by perched water from borehole SD-7 (Section A6.3.8.10). Both sets of 
models explain the major-ion chemistry and d13C values of groundwater at NC-EWDP-19D. 
The arrows leading from flow path 6 toward NC-EWDP-19D (Figure A6-62) reflect this 
alternative groundwater path. It should also be noted that the d18O and dD values of 
groundwater at well NC-EWDP-19D are substantially lighter than for groundwater at either 
wells WT-3 or WT-10, requiring that climate change be invoked as a possible explanation for 
their differences. 
Flow Path 8 (Figure A6-62) schematically illustrates leakage of groundwater from the carbonate 
aquifer (GF and AF Groups) across the Gravity fault. Hydrogeologists and geochemists have 
recognized this leakage across the fault for many years (Winograd and Thordarson 1975 
[DIRS 101167]; Claassen 1985 [DIRS 101125]). These hypotheses are also compatible with the 
hydraulic gradient and our understanding of the regional groundwater flow patterns (Lacziak 
et al. 1996 [DIRS 103012]). The carbonate aquifer component in this groundwater is recognized 
by many of the same chemical and isotopic characteristics that typify groundwater discharging 
from the carbonate aquifer at Ash Meadows. These characteristics include high concentrations 
of Ca2+ (Figure A6-20) and Mg2+ (Figure A6-21), low SiO2 (Figure A6-19), heavy d13C values 
(Figure A6-27), low 14C activity (Figure 6-28), and comparable d18O and dD values as the Ash 
Meadows groundwater. Westward seepage of this groundwater mixes with the southward flow 
of groundwater along path 3 to produce groundwater with compositions intermediate between 
the two (Section A6.3.7.2). Evidence for these flow paths is best defined in groundwater 
compositions of some of the more westerly samples of the GF group such as samples 160, 175, 
and 175 (Figure 6-50). 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-211 November 2004 
Flow path 9 (Figure A6-62) is drawn to schematically illustrate deep underflow of groundwater 
from the carbonate aquifer, east of and including the GF and AF groups, beneath the Amargosa 
Desert and Funeral Mountains to the discharge points in Death Valley. The similarity in the 
chemical and isotopic characteristics of groundwater found in the Gravity fault area and 
groundwater that discharges from springs at sites 201 (Nevares Spring) and 202 (Travertine 
Spring) support this interpretation. The dissimilarity in Cl (Figure A6-15), 
Mg2+ (Figure A6-21), and SiO2 (Figure A6-19) concentrations in these springs compared to the 
groundwater from the alluvial aquifer along the Amargosa River suggests that this alluvial 
groundwater is not the predominant source of the spring discharge in Death Valley. 
A6.3.11.1 Mixing Zones 
Figure A6-62 also highlights three zones (Mix A, B, and C) within which there is good evidence 
for mixing as demonstrated by trends of multiple solutes and isotope ratios on cross-correlation 
plots. Details of the mixing relations were given in Section A6.3.7. 
Mixing zone A is defined by YM-S and CF-SW samples along U.S. Highway 95. The mixing 
zone is indicated by groundwater compositions of samples 78 to 85, 89, and 90 that are 
intermediate between the compositionally distinct groundwater of the CF-SW group and dilute 
groundwater of the YM-S group that is interpreted to have originated in the Yucca Mountain 
area (see Figure A6-49 and the discussion of flow paths 6 and 7 in Section A6.3.11). The 
location of the southernmost CF-SW samples coincides with a steep hydraulic gradient 
(Figure A6-3), which remains steep to the west but decreases to the east. Evidence for the 
distinct groundwater of the CF-SW group in boreholes to the south in the Amargosa Desert is 
lacking (for example, Figure A6-50). Thus, hydrochemical data and the hydraulic gradient 
suggest that southward flow indicated by flow path 5 is effectively blocked to the south. This 
flow is at least partly diverted to the east where it mixes with more dilute groundwater of the 
YM-S group to the east. 
Mixing zone B consists of samples from the FMW-W and AR/FMW groups and a few samples 
from the FMW-S groups. The zone highlights groundwater with compositions that are 
intermediate between the distinct and consistent groundwater compositions of the AR group and 
the dilute groundwater of the FMW-S group (Figure A6-50). Flow path 1 is drawn to skirt the 
edge of mixing zone B and to connect the groundwater from the Amargosa River group to 
sample 181, which has a similar groundwater composition and is interpreted to represent 
undiluted groundwater from the AR group. 
Mixing zone C consists of all samples from the LW and FMW-E groups, a few of the more 
westerly samples form the GF group, and at least one sample (141) from the FMW-S group. The 
mixing zone is characterized by small percentages of the distinctively high SO4
2 groundwater 
from borehole J-11 (Figure A6-51) in groundwater near flow path 3. This distinct 
hydrochemical signature persists in variable percentages as far south as borehole 150. 
Groundwater with this distinctive signature is mixed to variable degrees with dilute water from 
the FMW-S group to the west or groundwater from the carbonate aquifer (GF Group) to the east. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-212 November 2004 
An important conclusion derived from identification of these mixing zones is that they 
qualitatively illustrate the extent of transverse dispersivity along certain flow pathways. The 
mixing zones also illustrate that, although some flow pathways may remain intact for great 
distances (e.g., paths 1 and 2), even these most-persistent flow paths eventually loose their 
distinct character, largely through mixing. This effect is best illustrated in southern Amargosa 
desert where flow paths 1, 2, and 3, with contributions from 8, converge and mix. The distinct 
end member groundwater of the AR and FMW-S groups, representing flow paths 1 and 2, 
appears to be absent at the southern boundary of the study area. Whereas it is possible that these 
end member groundwaters have not yet been sampled, the proximity of mixed groundwater 
samples in the southern part of the study area (samples 141, 174, 175, 183, 184, and 185) leaves 
little room for unmixed (end member) groundwater to move through the area. The 
hydrochemical data are interpreted to indicate that groundwaters from distinct sources that merge 
in the Amargosa Desert eventually lose their hydrochemically distinct character and flow 
southward as partially mixed groundwater. 
A7. SUMMARY, OUTPUT DATA TRACKING NUMBERS, AND UNCERTAINTIES 
A7.1 SUMMARY 
Hydrochemical data from the saturated zone in the Yucca Mountain region were compiled, 
documented, and analyzed in this appendix. The hydrochemical data are used together with 
physical hydraulic data to evaluate the local and regional flow system at Yucca Mountain. This 
report provides an independent assessment of the flow patterns (Section A6.3.11) and recharge 
rates (Section A6.3.6) near Yucca Mountain that can be compared with flow paths and recharge 
rates associated with the Site-Scale SZ flow model documented in Table 6-17. This report also 
provides an independent basis for calculating groundwater residence times (Section A6.3.9) that 
can be compared with particle breakthrough curves calculated using the site-scale SZ transport 
model. Additionally, this appendix contributes to the resolution of technical issues associated 
with groundwater residence times and flow path lengths in alluvium and tuff, as discussed below. 
The methods used in this appendix are widely accepted, the data are sufficient and the analysis 
appropriate for the intended use if this document. 
A7.1.1 Summary of Overview Sections (Sections A6.3.1 to A6.3.5) 
Areal distributions of chemical and isotopic data as well as calculated parameters show many 
consistent patterns throughout the study area. Groundwater that has low concentration of most 
solutes characterizes groundwater beneath Yucca Mountain and in Fortymile Wash. Dilute 
groundwaters characterize the northern part of Fortymile Wash as well as the southern part in the 
Amargosa Desert. Increases in most solute concentrations occur to the west of Yucca Mountain 
and along the southern margin of Yucca Mountain near U.S. Highway 95. Dilute groundwaters 
are flanked by less dilute groundwaters to the east and west in the Amargosa Desert. 
Hydrochemical data presented in these sections provide first-order constraints on flow pathways. 
Groundwater beneath Yucca Mountain and in Fortymile Wash is characterized by low 
concentrations of most solutes. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-213 November 2004 
Section A6.3.3 reveals that some wells display significant hydrochemical variability with depth. 
An important example is illustrated in the data from wells NC-EWDP-19D and -19P, which 
show that groundwater in all zones is similar to groundwater from the volcanic aquifer at 
Yucca Mountain, whereas groundwater in -19P is more chemically similar to groundwater in 
Fortymile Wash. These data illustrate potentially important information regarding flow 
pathways that may be obscured when only groundwater samples from open boreholes are 
available, as is the case for most data in this report. In the absence of additional discrete vertical 
sampling data, the two-dimensional analysis will form the basis of the flow-path analysis 
described herein. 
A7.1.2 Summary of Sources and Evolution of Recharge at Yucca Mountain 
(Section A6.3.6) 
Particular attention is given to this topic to set the stage for evaluation of flow from Yucca 
Mountain. Hydrochemistry of perched water is considered a reliable surrogate for potential 
recharge water. The hydrochemistry of perched groundwater is quite similar to that of 
groundwater beneath Yucca Mountain. Some perched water and groundwater beneath Yucca 
Mountain has similarly elevated 234U/238U activity ratios and relatively small uranium 
concentrations. Depth-dependent trends in uranium activity ratios of unsaturated-zone pore 
water and perched water are also consistent with a model for local recharge. Local recharge of 
groundwater beneath Yucca Mountain is also supported by hydrochemical evaluation of 
potential upgradient sources of groundwater. Significant hydrochemical differences between 
most of these waters argue against the possibility that significant percentages of upgradient 
groundwater are present at Yucca Mountain. It is therefore concluded that much of the water 
present beneath Yucca Mountain was derived from local recharge. 
Estimates of the magnitude of recharge at Yucca Mountain were obtained using the chloride 
mass balance method. For groundwaters within the immediate vicinity of Yucca Mountain, 
chloride concentrations range from 5.7 to 10.8 mg/L (excluding p#1-v), indicating local recharge 
rates between 4.7 and 17.9 mm/year using an average, present-day precipitation rate 
of 170 mm/year and an estimated range of Cl- concentrations in precipitation of 0.3 to 0.6 mg/L. 
The timing of recharge at Yucca Mountain was evaluated using hydrogen and oxygen isotopes as 
well as 14C ages. Although the hydrogen and oxygen isotope data do not place an absolute age 
on the groundwater, they do indicate that the groundwater was recharged under paleoclimatic 
conditions that existed until the late Pleistocene. Corrected groundwater 14C ages range 
from 11,430 years at borehole UE-25 WT#3 to 16 years at borehole UE-25 WT#12. These 
calculations are based on the averaged, that is, mixed age, of the groundwater sample. 
Calculations are also presented to bound the fraction of young water present in Yucca Mountain 
recharge. Estimates using an age of 1000 years for the young component range from a low of 
about 0.02 at borehole UE-25 WT#12 to more than 0.15 at boreholes UE-25 WT#3 and 
USW G-4. Smaller fractions of young water would be present if water younger 
than 1,000-year-old were assumed in the calculations. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-214 November 2004 
A7.1.3 Summary of Groundwater Flow and Evolution Away From Yucca Mountain 
(Sections A6.3.7 to A6.3.10) 
Areal distribution plots reveal regions where steep gradients in solute concentrations and isotopic 
signatures exist. Based on evaluating elemental and isotopic correlation and PHREEQC 
analyses, it is concluded that mixing does readily explain compositional gradients in some areas. 
For example, mixing explains the compositional gradient displayed by the Nye County wells 
along U.S. Highway 95 where dilute groundwater to the southeast mixes with groundwater with 
high solute concentrations present to the northwest. Mixing also readily accounts for many of 
the groundwater compositions found in the Amargosa Desert. Here, dilute groundwater present 
along the Fortymile Wash drainage in the central part of the Amargosa Desert mixes with 
groundwater to the east and west to produce intermediate compositions. It is also concluded that 
sulfate-rich groundwater similar to that found in well J-11 is present in the Amargosa Desert. 
PHREEQC analyses help to confirm mixing relationships and define other components that must 
be added or removed through water-rock interaction to achieve observed groundwater 
compositions. 
In Section A6.3.9, groundwater velocities are estimated along a selected flow path south of the 
repository in the Yucca Mountain area. Velocities are estimated by evaluating the 14C activities 
of the groundwater along the flow path in context with PHREEQC analyses of groundwater 
evolution. Estimated groundwater velocities along a linear flow path from WT-24 to WT-3 are 
46 m/year or higher. Groundwater velocities were also estimated along a flow path from WT-3 
to the various zones sampled at NC-EWDP-19D. These velocities range from approximately 
80 m/year to 5 m/year. The faster velocities are suggested to indicate that some of the shallow 
groundwater at well WT-3 moves along major faults such as the Paintbrush Canyon fault. 
The site-scale saturated zone flow model (or, simply, SZ flow model) was used to simulate the 
movement of a conservative tracer from various segments along the boundaries in the model 
(Section A6.3.10). Flow patterns and mixing relations identified with the SZ flow model were 
generally consistent with flow patterns and mixing relations inferred from the hydrochemical and 
isotopic data for the area. Of particular importance are simulations of the movement of recharge 
from the Yucca Mountain area. These simulations indicate that groundwater from 
Yucca Mountain may not be easily identifiable in groundwaters south of Yucca Mountain 
because of dilution by groundwater from other, more active parts of the flow system. This 
groundwater mixture includes contributions from northwest Crater Flat, Timber Mountain, and 
Fortymile Canyon. In some other respects, the SZ flow model differs from what is inferred from 
the geochemical data. For instance, the SZ flow model appears to underestimate the quantity of 
inflow from the Fortymile Canyon area through the Tertiary units. This conclusion is based on 
the observation that groundwater along Fortymile Wash through Jackass Flats and the Amargosa 
Desert is chemically and isotopically unique compared to the surrounding groundwaters, but the 
tracer simulations indicate that groundwater inflow from Fortymile Canyon or from 
downgradient recharge along the wash is present only in dilute amounts along Fortymile Wash. 
Some of the discrepancy between the simulations and the data for the Fortymile Wash area may 
be due to recharge of some or most of this chemically distinct groundwater during wetter climate 
periods. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-215 November 2004 
A7.1.4 Summary of Flow Pathways (Section A6.3.11) 
Flow paths can be traced using areal plots and scatterplots of geochemical and isotopic data, 
inverse mixing and water/rock interaction analyses involving PHREEQC, and simulations done 
with the SZ flow model. Because no single chemical or isotopic species varies sufficiently to 
determine flow paths everywhere in the study area, multiple chemical and isotopic species were 
considered. 
Flow Path 1 (Figure A6-62) 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. 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 central Jackass Flats near well J-11 through the eastern part of the 
Amargosa Desert. Flow Paths 4 and 5 shows groundwater moving predominantly 
south-southeast through Crater Flat. Mixing relations and modeling suggest that these 
groundwaters leak across a region with a steep hydraulic gradient to mix with more dilute 
groundwaters to the southeast. Flow Paths 6 and 7 show groundwater flow from the Solitario 
Canyon area to the south. Again, leakage to the southeast across a steep hydraulic gradient 
coincident with the Solitario Canyon fault is suggested by hydrochemical trends. Groundwater 
from northern Yucca Mountain is interpreted to flow southeast toward lower Dune Wash and 
then southwestward toward wells located west of Fortymile Wash near U.S. Highway 95 
(Flow Path 7). The location of Flow Path 7 implies that groundwater from the repository area 
will flow further to the west of this path. Flow Path 8 illustrates leakage to the east across the 
hydrologic boundary between the carbonate aquifer to the east and the alluvial aquifer in 
Amargosa Desert. Flow Path 9 schematically illustrates deep underflow of groundwater from the 
carbonate aquifer, east of and including the GF and AF groups, beneath the Amargosa Desert 
and Funeral Mountains to the discharge points in Death Valley. 
Regions where mixing relations are strongly suggested by hydrochemical data are also shown in 
Figure A6-62. An important conclusion derived from drawing these mixing zones is that they 
document and qualitatively illustrate the extent of transverse dispersivity along certain flow 
pathways. The mixing zones also illustrate that although some flow pathways may remain intact 
for great distances (e.g., Paths 1 and 2), even these most persistent flow paths eventually lose 
their distinct character largely through mixing as is demonstrated in southern Amargosa Desert 
along the southern border of the map area. 
A7.2 DATA TRACKING NUMBERS 
Several data tracking numbers (DTNs), generated in this appendix are cited elsewhere in this 
report where they are used as indirect input. These are listed below in an order that coincides 
with the structure of the appendix. These results are not qualified and cannot be used as direct 
input without qualification: 
Regional groundwater hydrochemical data: DTNs: LA0309RR831233.001 [DIRS 171890] and 
LA0309RR831233.002 [DIRS 171890] 
Calculated hydrochemical parameters: DTN: LA0310EK831232.001 [DIRS 165995] 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-216 November 2004 
Calculation of corrected and uncorrected groundwater 14C ages: DTN: LA0202EK831231.002 
[DIRS 165507] 
Calculations of fractions of young water in selected Yucca Mountain groundwaters: 
Output DTN: LA0202EK831231.004 
Groundwater travel-time calculations for selected wells: DTN: LA0310EK831231.001 
[DIRS 171889] 
FEHM groundwater models of nonreactive tracer transport in the Yucca Mountain area: 
DTN: LA0309EK831231.001 [DIRS 171887] 
A map of groundwater flow paths in the Yucca Mountain area: DTN: LA0308RR831233.001 
[DIRS 171890]. 
A7.3 UNCERTAINTIES AND RESTRICTIONS 
The evaluations and conclusions presented in this appendix are interpretive in nature. The 
overall uncertainty of these interpretations is a function of the analytical uncertainty of the data 
on which the interpretations were based, the distribution of data both areally and with depth, the 
representativeness of these data for various parts of the groundwater system, and the uncertainty 
in the conceptual models that formed the framework for the interpretations. 
Results presented in this appendix are affected to different degrees by each of these uncertainties. 
The following sections list the key uncertainties associated with each of the DTNs cited in 
Section A7.2. 
A7.3.1 Compilation of Hydrochemical Data 
The uncertainty associated with the DTNs results primarily from the analytical uncertainty 
associated with the measurements and the representativeness of the data for those parts of the 
aquifer from which the groundwater samples were taken. Ideally, groundwater samples are 
taken after the well has been pumped for some time after drilling so that the effects of foreign 
drilling fluids and borehole cuttings on in situ groundwater compositions have been mitigated. 
Although this is true of the vast majority of the samples used in this report, a small number of 
samples used in this report originated from wells in which the samples were bailed prior to a 
clean-out period. This approach may have caused the chemical characteristics of these 
samples to change somewhat relative to in situ groundwater. In general, bailed samples were 
used in this report only if later pumped samples were not available from a particular well. The 
representativeness of sampled groundwater of in situ groundwater compositions is also related to 
the depth interval over which the sample was taken. Most hydrochemical data reported here are 
from single-interval boreholes, the hydrochemistry of which will represent an average of the 
sampled depth intervals. Hydrochemical data for discrete depth intervals are presented in 
Section 6.7.3. 
The representativeness of sampled groundwater of in situ conditions may also be affected by the 
sampling method. For example, choice of container or prolonged exposure to atmosphere may 
affect groundwater chemistry. Most sample data presented herein were collected by the United 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-217 November 2004 
States Geological Survey (or by their contractors), who have a long and proven record of 
groundwater sampling using proven techniques. Furthermore, Yucca Mountain Project Quality 
Assurance Programs also govern many of these sampling procedures. This program is designed 
to assure that methods utilized are appropriate for the desired purpose. Thus, the data are 
accepted to be representative of in situ conditions. All analytical data presented herein have 
uncertainty associated with the individual values. These uncertainties reflect limits of precision 
of the analytical technique combined with accuracy of the measurement, which is typically 
determined by replicate analysis of samples (standards) with known values. The data presented 
herein were determined using a variety of analytical techniques by a number of laboratories, 
collected over a span of more than 20 years, during which time analytical techniques and 
associated uncertainties have changed. In some cases, uncertainties for individual analytes or 
groups of analytes are presented in the original data sources, however, in other data sets 
analytical uncertainties are neither given nor discussed. Some examples of stated uncertainties 
are presented below. 
The National Water Quality Laboratory produced many of the data presented herein for the 
Yucca Mountain Program at the United States Geological Survey and uncertainties are stated in 
some of the DTNs. For example, accuracy for major anions, cations and strontium concentration 
is estimated to be better than 10 percent except for fluoride, which is estimated at 15 percent 
(DTN: GS000308312322.003 [DIRS 149155]). Uncertainty in concentration of major anions 
and cations as well as strontium concentration is quoted at less than 10 percent in 
DTN: GS011108312322.006 [DIRS 162911]. This DTN also presents uncertainties for isotopic 
measurements as follows (all given in per mil): deuterium 3.0, 18O 0.2, 13C 0.2 and 34S 0.2. In 
some cases, strontium was determined by isotope dilution, mass spectrometry methods, for 
which data are more precise (e.g. 0.5 percent, DTN: GS970708315215.008 [DIRS 164674]). 
Uncertainties for 14C are 0.1 pmc for data presented in DTN: GS011108312322.006 
[DIRS 162911]. Uncertainties for uranium concentration are given as better than 1 percent 
(Paces et al 2002 [DIRS 158817]). Uncertainties in uranium isotope ratios (234U/238U) are 
typically given with each individual analysis in the original data source. For example, 
uncertainties presented in Paces et al. (2002 [DIRS 158817], Table 2) range from 0.09 percent 
to 4.5 percent with a mean of 0.73 percent (with the exception of a single analysis of a rainfall 
sample with small U concentration for which uncertainty in the 234U/238U ratio is 9.8 percent). 
Uncertainties for strontium isotope ratios (87Sr/86Sr) are typically quoted at 0.00001 for absolute 
values (e.g. DTN: GS011108312322.006 [DIRS 162911] and for Nye County wells), which 
translates to an uncertainty of approximately 0.01 in d87Sr units. 
For the purpose of this report, uncertainties assigned to analytical data are based on one or more 
of the following: (1) stated uncertainties in the original data set; (2) consideration that data 
produced by the same facility, for which no uncertainties are stated, are likely to have similar 
uncertainties to data with stated uncertainties; (3) typical uncertainties given in the literature; 
or (4) the authors personal experience with typical uncertainties associated for various analytical 
techniques and analytes. Where uncertainties are not stated, the following uncertainties are 
assigned to the analytical data: Major anions and anions and strontium concentration: 
10 percent; fluoride concentration: 15 percent; stable isotopes of hydrogen, oxygen, sulfur, and 
carbon (expressed as dH, dO, dS, and dC in per mil): 0.2; and 14C: 0.2 pmc. Uncertainties in 
uranium concentration and uranium and strontium isotope ratios are given in the original data 
sets. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-218 November 2004 
In addition to analytical errors, many of the samples in the portion of the data set that had no 
prior DTNs may have an additional uncertainty in that they were obtained from a database 
(geochem02.mdb) that does not represent the primary source of the data. Hence, the possibility 
of transcription errors is compounded. Where original published sources could be found and 
checked against that database, some transcription errors in the database were evident. This 
uncertainty affects only groundwater samples at locations to the west, north, and east of the site 
model area, outside of the site model area. 
It is prudent to point out that most of the evaluations presented herein are based on 
hydrochemical groupings and general data trends displayed within and among these groupings as 
opposed to any one analysis or data set from any one sample. Generally, the range of analytical 
values displayed within a single hydrochemical grouping is greater than the analytical 
uncertainty for any individual analysis. Hydrochemical groupings and data trends remain valid 
and essentially unaffected by considerations of analytical uncertainty. 
A7.3.2 Calculated Hydrochemical Parameters 
The uncertainty in the calculated hydrochemical parameters reflects the analytical uncertainty of 
the measurements, the representativeness of these measurements of in situ groundwater 
conditions, and uncertainty in the solubility constants of the minerals for which saturation indices 
were calculated. Uncertainty in the applicability of the solubility constants arises from 
(1) inaccurate, incomplete or inconsistent thermodynamic data, (2) nonstoichiometric or variable 
mineral compositions, (3) differences in the particle sizes of minerals that produced the 
thermodynamic data and particle sizes of minerals to which the data were applied, (4) model 
assumptions and limitations, such as which aqueous complexes are considered in the model, and 
(5) kinetic effects arising from slow reaction rates relative to groundwater residence times 
(Langmuir 1997 [DIRS 100051], p. 221). In addition, because solubility constants are a function 
of temperature, uncertainty in groundwater temperatures affects the calculated saturation indices. 
Measured groundwater temperatures were used to calculate saturation indices for most wells 
considered in this report. For a relatively small number of wells in the Yucca Mountain area, 
groundwater temperatures were estimated from published maps of water table temperatures. 
Groundwaters in the Amargosa Desert with no temperature data were assumed to be at 25C 
based on the measured groundwater temperatures of nearby wells. A sensitivity analysis to 
examine the effect of temperature changes on log PCO2 and mineral saturation indices for 
groundwater from well J-13 indicated the following uncertainties as assumed temperatures were 
varied by 5C around 25C: log PCO2 (0.06), SIcalcite (0.04), SIsmectite (1.72), SICa-clinoptilolite 
(4.77), SISiO2(a) (0.04), SIfluorite (0.06), SIalbite (0.28), SIK-feldspar (0.34), and SIdolomite (0.14). 
Saturation indices for calcite and dolomite and log PCO2 increase with temperature, but the 
remaining saturation indices decrease with temperature. The saturation indices of smectite and 
Ca-clinoptilolite are particularly sensitive to temperature because of the large enthalpies 
estimated for these minerals (Table A6-4); however, groundwaters in the Amargosa Desert are 
typically very supersaturated with these minerals (Figures A6-38 and A6-39), so that a 
temperature uncertainty of 5C does not change the fundamental conclusion that groundwaters 
in the Amargosa Desert are supersaturated with these minerals. For other minerals, uncertainty 
in groundwater temperatures of 25 5C introduces less absolute uncertainty into the calculated 
saturation indices. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-219 November 2004 
Another source of uncertainty in the calculated saturation indices of alumino-silicate minerals 
concerns the assumption that total dissolved Al3+ concentrations are in equilibrium with 
kaolinite. This assumption was based on an empirical fit to dissolved Al3+ concentrations from a 
subset of the Yucca Mountain area wells for which dissolved Al3+ data exist (see 
Section A6.3.5). Estimates of Al3+ concentrations that rely on assumed equilibrium with 
kaolinite underestimate measured Al3+ concentrations by 3.0 2.9 ppb. If the actual Al3+ 
concentrations were approximately 3 ppb higher than was estimated for the Yucca Mountain 
area, the saturation indices of all Al-bearing minerals would increase. Assuming Al3+ 
equilibrium with kaolinite, most groundwaters in the Yucca Mountain area are estimated to be 
saturated with smectite and Ca-clinoptilolite (Figures A6-38 and A6-39). With higher 
Al3+ concentrations, these groundwaters would be even more supersaturated with these minerals. 
Groundwaters in the Yucca Mountain area are presently estimated to be both undersaturated and 
supersaturated with K-feldspar (Figure A6-37). With higher Al3+ concentrations, some 
groundwaters that are estimated to be undersaturated with K-feldspar might be calculated to be 
saturated or supersaturated with K-feldspar. 
A7.3.3 Calculated 14C Ages 
The calculations of 14C ages used the downgradient increase in the DIC concentrations of 
selected Yucca Mountain area groundwaters, relative to the DIC concentrations of 
Yucca Mountain perched waters to estimate the extent of 14C dilution by calcite dissolution in 
the saturated zone (Section A6.3.6.6.2). The selected groundwater samples were chosen because 
they, like the perched water samples, had high 234U/238U activity ratios relative to many 
Yucca Mountain area groundwaters, thus indicating the likelihood of a common origin. The 
estimated increases in the DIC concentrations of the groundwaters were then used to reduce the 
initial 14C activities to below their original atmospheric values to calculate a corrected 14C age 
for the groundwater. The critical assumptions in this analysis are that (1) the perched water itself 
required no age corrections and (2) that the measured increases in groundwater DIC relative to 
perched water limit the amount of 14C dilution by calcite. Assumption (1) appears to be valid 
based on the historic variations of 36Cl/Cl and 14C activities measured on organic carbon in 
pack-rat middens and similar relations between 36Cl/Cl and 14C activities measured for inorganic 
carbon in perched water. Assumption (2) requires that no reductions in groundwater DIC 
concentrations take place through exsolution of CO2 during groundwater flow or during 
sampling. Although CO2 losses from groundwater to the unsaturated zone are estimated to be 
small because of the low diffusion of CO2 in groundwater, exsolution of CO2 during 
groundwater sampling may be a more significant effect. However, groundwater at the wells 
where 14C age corrections were made typically had relatively low (< 7.8) pH values, indicating 
that the effects of degassing on DIC concentrations during sample collection were minimal. 
A7.3.4 Calculations of the Fractions of Young Water in Yucca Mountain 
Groundwaters 
These calculations interpret the measured 14C activities of groundwater beneath Yucca Mountain 
to result from the mixing of groundwater that has been recharged at different times from the 
unsaturated zone at Yucca Mountain. Although recharge may have been added continuously 
over time at varying rates to Yucca Mountain groundwater, the calculations simplify the actual 
distribution by assuming that the measured 14C activities result from the mixing of an old 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-220 November 2004 
component and a young component that are widely separated in time. This approach 
effectively replaces the actual (but unknown) distribution of groundwater ages by a bimodal 
distribution of ages with the same mean age. This idealized distribution of ages places more 
emphasis on the very young and very old groundwaters than the actual age distribution would 
indicate. This method provides upper bounds to the fraction of young groundwater in the 
mixture, which is the quantity of interest in these calculations. 
A7.3.5 PHREEQC Inverse Models of Groundwater Mixing and Water-Rock Interaction 
The PHREEQC inverse models of groundwater mixing and water-rock interaction described in 
Section A6.3.8 are affected by uncertainties in the accuracy and representativeness of 
groundwater compositions (see Section A7.3.1), uncertainties in mineral-phase compositions, 
and uncertainties in the conceptual model. The uncertainties in the accuracy and 
representativeness of groundwater compositions are accounted for in the PHREEQC models 
through user-specified uncertainty criteria. Generally, uncertainties specified in the PHREEQC 
models were 10 percent or less of the measured concentrations for major and minor 
ions, 0.1 per mil for d18O, 1.0 per mil for dD, 0.1 per mil for d13C, and 0.05 pH units for pH. 
These uncertainties were intended to reflect not only analytical uncertainty in the measurements 
(See Section A7.3.1) but also the representativeness of the groundwater samples in light of the 
chemical and isotopic heterogeneity that exists in groundwaters from closely spaced wells. It 
was necessary to specify some uncertainty in these models in order to simultaneously satisfy the 
multiple mass-balance constraints involved in any particular model. There is also some 
variability in mineral phase compositions from Yucca Mountain and, hence, some uncertainty in 
specifying a single representative phase composition for the entire area. This variability is 
particularly true of clinoptilolites, which are known to have east-to-west chemical variations 
across the Yucca Mountain area (Broxton et al. 1987 [DIRS 102004]). Generally, clinoptilolite 
compositions used in any particular model were chosen to be representative of the area near the 
wells considered by that model. For reactions involving the dissolution or precipitation of calcite 
(or dolomite), it was necessary to specify the d13C composition of the calcite. The d13C 
compositions are variable in SZ calcites and, therefore, some uncertainty exists in choosing a 
single representative value. Calcite in the volcanic aquifers was assumed to have d13C values of 
between 43 and 13 per mil, whereas calcite in the alluvial aquifers near Fortymile Wash 
was assumed to be 43 per mil. Although the values of d13C used for the volcanic aquifer are 
in agreement with measured values (Whelan et al. 1998 [DIRS 137305]), the isotopic 
characteristics of calcite in alluvium have not been measured at Yucca Mountain. The calcite in 
alluvium was assumed to have isotopic characteristics (d13C = 4 per mil) similar to pedogenic 
calcite at the surface of Yucca Mountain (Table A5-1 in Assumption 9). 
The specified uncertainty in solution compositions and in the isotopic composition of the 
minerals is propagated through the PHREEQC inverse models so that, for each model, upper and 
lower bounds are also estimated for the mixing ratios and amounts of each mineral phase 
dissolved. However, although quantitative measures of uncertainty are provided for each model 
discussed in this report (DTN: LA0310EK831232.001 [DIRS 165995]), these uncertainty 
estimates do not consider the other combinations of mineral reactions and mixing end members 
present in alternative models identified by PHREEQC. Additionally, these uncertainty estimates 
do not consider the conceptual model uncertainty. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-221 November 2004 
Conceptual-model uncertainty includes the choice of mineral phases to be considered in a 
particular model, any constraints on the precipitation/dissolution or exchange reactions imposed 
on these phases, and the choice of groundwaters considered in these models as potential mixing 
components. The rationale behind selection of these various parameters is discussed in 
Section A6.3.8. It is acknowledged; however, that all possible combinations of these parameters 
were not exhaustively evaluated. Other combinations of end-member mixing components and 
reaction history could possibly be modeled to yield a particular downgradient water chemistry. 
Given all the potential combinations of mixing end members and reaction models, it is 
impossible to quantify uncertainty related to uncertainties in the conceptual model. 
A7.3.6 Groundwater Velocities 
The groundwater velocities calculated in Section A6.3.9 were based on the measured 
groundwater 14C activities at wells defining a flow path segment, the linear distance between the 
wells, and the water-rock interactions identified by the PHREEQC models for that flow-path 
segment. The calculated velocities are, therefore, affected by the accuracy and 
representativeness of the groundwater 14C measurements (see Section A7.3.1), the assumption 
that groundwater flows along a straight path between the wells defining the flow-path segment, 
and the uncertainties associated with the PHREEQC models, as described in Section A7.3.5. An 
indication of the quantitative uncertainty associated with transit times is provided by the standard 
deviations associated with transport times based on the PHREEQC models and differences 
between the means of these estimates and estimates made based on downgradient increases in 
DIC concentrations (Table A6-11). An additional uncertainty that may impact these calculations 
concerns the implicit assumption that no additional 14C is added to the groundwater from 
downgradient recharge as the groundwater moves from the upgradient to downgradient wells 
defining a flow-path segment. Recharge at Yucca Mountain may not vary enough spatially to 
guarantee that upgradient and downgradient recharge could be recognized in a mixture. 
A7.3.7 FEHM Groundwater Models of Nonreactive Tracer Transport in the Yucca 
Mountain Area 
The FEHM simulations of nonreactive tracer transport described in Section A6.3.10 used the 
Yucca Mountain site-scale saturated zone flow model documented in Table 6-17. Uncertainties 
associated with this flow model are documented therein. An additional uncertainty that pertains 
to the tracer simulations but not the flow model itself concerns numerical dispersion associated 
with the advection/dispersion equation. Numerical dispersion would tend to cause greater 
apparent mixing and dilution than would be present solely because of hydraulic conductivity 
variations in the model. These effects are likely to have influenced the tracer concentration 
distributions shown in Section A6.3.10 and, in particular, the relatively dilute concentrations near 
the edges of these tracer plumes may be an artifact of this numerical dispersion. 
A7.3.8 A Map of Groundwater Flow Paths for the Yucca Mountain Area 
The map of groundwater flow paths in the Yucca Mountain area (Figure A6-62) was developed 
on the basis of areal variations of chemical and isotopic species (Section A6.3.4), scatterplots 
that indicated mixing between groundwaters from different areas (Section A6.3.7), and 
PHREEQC models of groundwater mixing and chemical evolution (Section A6.3.8). The 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-222 November 2004 
flow-path map is affected, therefore, by the uncertainties already described for these outputs in 
Sections A7.3.1, A7.3.2, and A7.3.5. 
Possibly, the most important uncertainty in the flow path map relates to the source of the 
groundwater at well NC-EWDP-19D (Sites 92 and 9498). Two equally plausible sets of 
groundwater mixing and reaction models were developed with PHREEQC for groundwater at 
well NC-EWDP-19D, each of which implies a different direction for groundwater flow from the 
repository area in southern Yucca Mountain. The first set of models indicates that groundwater 
from various depths at NC-EWDP-19D originates from groundwater in the Dune Wash area 
(represented by groundwater from well WT-3) and a set of water-rock-gas reactions. These 
results are represented on the flow-path map as the southern part of Flow Path 7. Groundwater 
from the repository area would be constrained by the southern part of Flow Path 7 to move 
predominantly southward or southwestward through southern Yucca Mountain, thereby avoiding 
most of the alluvium north of U.S. Highway 95. The second group of PHREEQC models for 
groundwater from various zones in well NC-EWDP-19D indicated that these groundwaters are a 
mixture of groundwaters from the Solitario Canyon Wash area (represented by groundwater from 
well WT-10) and local Yucca Mountain recharge (represented by perched water from borehole 
SD-7), plus a set of water-rock reactions. This origin for the groundwater at well 
NC-EWDP-19D indicates that groundwater from the repository area will follow a more 
southeasterly trajectory and would probably encounter more of the alluvium west of Fortymile 
Wash than is indicated by Flow Path 7. The leakage of groundwater from the Solitario Canyon 
area across the Solitario Canyon fault beneath Yucca Mountain is indicated by the 
southeast-trending arrows originating from Flow Path A6. 
A8. RESULTS, LISTED BY DATA TRACKING NUMBER 
These results are not qualified and cannot be used as direct input to models or scientific analyses 
without qualification: 
LA0202EK831231.002 [DIRS 165507] Calculation of Corrected and Uncorrected Groundwater 
Carbon-14 Ages. Submittal date: 02/25/2002. 
LA0202EK831231.004. Calculation of the Maximum Possible Percentage of 1000 Year-old 
Water Present in Selected Yucca Mountain Area Groundwater Samples. 
Submittal date: 02/25/2002. (output). 
LA0308RR831233.001. Regional Groundwater Flow Pathways in the Yucca Mountain Area 
Inferred from Hydrochemical and Isotopic Data.. Submittal date: 08/25/2003. 
LA0309EK831231.001. SZ Flow and Transport Model, FEHM Files for Tracer Transport. 
Submittal date: 09/02/2003. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-223 November 2004 
LA0309RR831233.001. Regional Groundwater Hydrochemical Data in the Yucca Mountain 
Area Used as Direct Inputs for ANL-NBS-HS-000021, Rev. 01. Submittal date: 05/09/2003. 
LA0309RR831233.002. Regional Groundwater Hydrochemical Data in the Yucca Mountain 
Area Used as Corroborative Data for ANL-NBS-HS-000021, Rev. 01. 
Submittal date: 05/09/2003. 
LA0310EK831231.001. SZ Geochemical Calculations, Groundwater Travel Times for Selected 
Wells. Submittal date: 10/16/2003 
LA0310EK831232.001. SZ Geochemical Models, PHREEQC Files for Selected Groundwater 
Parameters. Submittal date: 10/02/2003. 
Saturated Zone Site-Scale Flow Model 
MDL-NBS-HS-000011 REV 02 A-224 November 2004 
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