UNITED STATES

NUCLEAR WASTE TECHNICAL REVIEW BOARD

PANEL ON THE NATURAL SYSTEM

SATURATED ZONE FLUID FLOW AND RADIONUCLIDE TRANSPORT

Wednesday, March 10, 2004

Crown Plaza Hotel

4255 South Paradise Road

Las Vegas, NV 89109

Tel: (702) 369-4400

Fax: (702) 369-3770

[BOARD MEMBERS PRESENT]{.underline}

Dr. Daniel B. Bullen, Chair, Afternoon Session

Dr. Thure Cerling

Dr. Ronald Latanision

Dr. Priscilla P. Nelson, Chair, Morning Session

Dr. Richard R. Parizek, Chair, Panel on the Natural System

[SENIOR PROFESSIONAL STAFF]{.underline}

Dr. Carl Di Bella

Dr. Daniel Fehringer

Dr. Daniel Metlay

Dr. Leon Reiter

Dr. David Diodato

Dr. John Pye

[CONSULTANTS]{.underline}

Dr. Frank Schwartz, Ohio State University

Dr. Rien van Genuchten, USDA/ARS

[NWTRB STAFF]{.underline}

Dr. William Barnard, Executive Director

Linda Coultry, Management Assistant

Alvina Hayes, Office Assistant

[I N D E X]{.underline}

[PAGE NO.]{.underline}

**Session Introduction**

Priscilla Nelson, Member,

Panel on the Natural System, NWTRB. . . . . . . . . 313

**Ground-water flow system of the Death Valley Region**

Claudia Faunt, USGS/Yucca Mountain Project. . . . . 316

**Inyo County investigations of flow in fault zones**

**south of Yucca Mountain**

John Bredehoeft, The Hydrodynamics Group. . . . . . 353

**Ground-water flow system of the Yucca Mountain area**

James Winterle, Center for Nuclear Waste Regulatory

Analysis, Southwest Research Institute. . . . . . . 381

**Conceptual model of saturated zone flow and transport**

**and independent lines of evidence for evaluating DOE**

**saturated zone model predictions**

Ken Rehfeldt, BSC/Los Alamos National Laboratory. . 412

**Public Comments** . . . . . . . . . . . . . . . . . . 438

**Session Introduction**

Daniel Bullen, Member, Panel on Natural System,

U.S. Nuclear Waste Technical Review Board . . . . . 449

**Geochemical mapping of the ground-water system**

Gary Patterson, USGS/Yucca Mountain Project . . . . 452

**Sorption, matrix diffusion, and colloid-facilitated**

**transport in saturated zone radionuclide transport**

**models**

Stephanie Kuzio, BSC/Sandia National Laboratory . . 478

**Saturated zone radionuclide transport predictions and**

**abstractions of Total System Performance Assessment**

Bill Arnold, BSC/Sandia National Laboratory . . . . 499

**Open Forum**. . . . . . . . . . . . . . . . . . . . . 534

**Public Comment**. . . . . . . . . . . . . . . . . . . 574

**Adjourn** . . . . . . . . . . . . . . . . . . . . . . 578

[P R O C E E D I N G S]{.underline}

(8:00 a.m.)

NELSON: Good morning and welcome back to this meeting of the Nuclear
Waste Technical Review Board, Panel on the Natural System. I am
Priscilla Nelson and I\'m one of the panel members for this Board Panel.
Today, we continue the theme of hydrogeology, fluid flow, and solute
transport, but the focus now turns to how those processes operate in the
saturated zone of Yucca Mountain following the unsaturated zone
consideration yesterday. You may recall that yesterday we presented a
list of questions that outline the central purpose of this two day
meeting. And, here is the list of questions again.

Each of today\'s talks will address one or more aspects of these
questions. At the end of the day after all of the technical
presentations are concluded, we will have a roundtable discussion forum
that will include Board members, Board consultants, presenters, and
others as identified and I hope you\'ll all stay to participate in that
discussion. Time permitting, we might even allow the Board Staff a few
questions. I want to call your attention to the Board Staff sitting over
to my left.

The first talk of the day will be given by Claudia Faunt of the USGS.
That talk will present the USGS model of the entire Death Valley
regional groundwater flow system of which Yucca Mountain is a part. And,
after that presentation, John Bredehoeft of the Hydrodynamics Group will
talk about investigating the role that faults play in controlling flow
through the Funeral Mountains on the west side of the Amargosa Valley,
work that his company is doing for Inyo County. After a short break, Jim
Winterle of the Center for Nuclear Waste Regulatory Analyses will
present his model of the groundwater flow system in the Yucca Mountain
area, including investigations of the effect of climate change on the
local groundwater flow system. The final talk of the morning will be
given by Ken Rehfeldt from Los Alamos National Laboratory and he will
present the DOE\'s conceptual model of saturated zone flow and transport
and independent lines of evidence for evaluating DOE saturated zone
model predictions. So, we have an excellent second day for the panel
following a very interesting first day yesterday.

As is normal, just before lunch we have set aside a period of time for
public comment and this period is intended for people who, for one
reason or another, cannot wait until the comment period that\'s
scheduled at the end of the day. Some people may simply not be able to
stay for the entire program. I know it\'s early, but is there anyone
here who already knows that they will not be able to stay until the end
of the day for that comment period so that we make sure that we have
time for them at the noon break?

(Pause.)

NELSON: I see a few hands. Well, that\'s great. Please, make sure to
sign up so that we know who you are. And, by signing up, we mean to go
to the desk where Linda and Alvina are raising their hands right now and
sign in so that we know that you do indeed want to make a comment.

If you prefer at any point during the day, you can submit written matter
for the record to Linda or Alvina. You can also pose questions through
the Board themselves. As a reminder, please, silence your cell phones
before we start today.

And, with these preliminaries out of the way, it\'s my pleasure to
introduce Claudia Faunt. Claudia Faunt received her degrees from the
Colorado School of Mines in geological engineering, one of my favorite
fields of study. Dr. Faunt is currently a hydrologist in the San Diego
Project Office of the USGS. She is a leader and member of the Death
Valley regional groundwater flow system project, and in that capacity,
she has studied water resources in southern Nevada and California.
Utilizing geographic information systems and 3-D geologic modeling and
visualization tools, she specializes in integrating geologic information
into groundwater studies and that\'s an integration we\'re all
interested in.

So, the floor is yours, Claudia. Thanks.

FAUNT: Good morning. I\'m going to talk about kind of a large regional
flow system model. It\'s kind of a group effort that we\'ve put together
over a large number of years. These are the different people on the
team. It\'s split a little with people all over the western United
States from Denver, Tucson, Sacramento, Boulder, California, San Diego,
and a lot of people in Las Vegas, as well. It\'s kind of a mixture
between people in water resources division of the U.S. Geological
Survey, as well as geologic division.

Kind of an overview of my talk, this is kind of the topics I\'m going to
go through. I\'m going to talk a little bit about the conceptual models
and the geologic emphasis of this project, the tasks that we\'re going
through this year, describe some of the regional groundwater flow model
we\'ve put together, go into a little bit of detail on one of the
particular uses of the model which is fluxes in and out of the
site-scale model at Yucca Mountain, talk a little bit about the report
outline for the report that\'s coming out the end of the year, and then
some questions.

This is a map showing the Death Valley regional flow model area. It\'s a
large area with pretty complex geology. One of the unique features about
the model is it\'s been put together with two major funding sources.
It\'s been funded about 50 percent by Yucca Mountain Project and
probably about 50 percent by the Department of Energy and their
different funding parts with the Nevada Test Site work with the
underground testing area program, the defense program, and a number of
different funding sources.

The model we\'re putting together now is kind of an update of a number
of previous modeling efforts that were done partially by the Survey and
partially by consultants and DOE to try to combine all the data that
exists from these models and databases that are put together to support
those models and the different information learned from those models and
a lot of new geologic work that\'s been done in the last three or four
years. It\'s being constructed using MODFLOW-2000. It\'s actually a
transient model that covers the time period from 1913 to 1998.

The study area, if you are familiar with it, goes from\--Las Vegas is
over here on the southeastern edge, Nevada Test Site is in here, Yucca
Mountain is right along in here. Death Valley which is kind of the
ultimate discharge area for the system is over in here. It\'s a pretty
big area. The kind of brown box surrounding it covers about 100,000
square kilometers. The model goes from land surface down to 4,000 meters
below sea level and it\'s covered by about 16 layers.

To kind of look at a conceptual model of the flow system, it\'s kind of
part of the carbonate rock aquifer kind of carbonate system. But, this
carbonate system has been interrupted by a number of large-scale basin,
range style type faults. So, there\'s large mountain blocks with
intervening valleys. Most of the pumping occurs in these valleys that
are between these mountain ranges. The carbonate rock forms a very
permeable regional system that connects a lot of the system. A lot of
low-permeability rocks are also involved in this faulting and form block
structures and cause a lot of the discharge in the system. A lot of
springs, such as Ash Meadows, are situated along faults and structures.

So, we\'ve spent a lot of time looking at geology and part of that is,
if you look at Darcy\'s Law, you can split it into two pieces and half
of it is basically considered the framework or kind of the geologic
component and half of it is the hydrologic component. And, the studies
and why there\'s a large team putting together this effort have been
split into these, you know, different subject matters and different
people are focusing on different portions and then they\'re being pulled
together in building the groundwater flow model.

The framework is where I\'ve concentrated on and it\'s kind of where a
lot more of this talk will be oriented. It talks about some of the
heterogeneity and the aquifers and confining units and their
distribution. Hydrology is a lot of the water level data, the pumping
data, some of the infiltration which Alan Flint talked about yesterday,
discharge that Randy Laczniak did a lot of work on.

So, the geologic interpretations that support the model. For the last
three or four years ending about a year ago, a large mapping was done in
the region and synthesizing existing geologic maps. These were compiled
together. There was kind of an interpretation of the tectonics. It was
consistent for the entire region. Before, there was different structural
styles studied and mapped in different areas and this was an attempt to
integrate those into a consistent tectonic picture for the entire
region. In doing that, about 32 regional geologic cross-sections were
built. These are new ones that are about a 1 to 250,000 scale. A number
of geophysical studies were done, gravity and magnetics, in particular,
mostly looking at the area around the test site, and some of the
magnetics and gravity were studied intensively around Pahrump Valley, as
well.

Part of the extra geophysical data led to some stratigraphic analysis of
some of the tertiary basins and this has been particularly helpful in
some of the transient runs where we needed more data to look at the
pumping scenarios and when water level declines where because if we had
more information, then more geologic information was necessary to
support the differences. And, there was some work by Don Sweetkind and
others to look at the hydrologic significance of some of the structural
and stratigraphic elements.

The way this geologic information was integrated into the flow model was
building a three-dimensional geologic model. This is kind of a cut into
the geologic model or cross-sections through the model. If you start to
look at below the land surface, you start to see this aqua color which
represents the paleozoic carbonate rock aquifer. And, you can start to
see where it\'s connected and where it\'s not. In the north-central
portion of the study area is this large volcanic field of southwestern
Nevada volcanic field and a lot of the volcanics at Yucca Mountain are
part of the southern end of this volcanic field. These are kind of
superimposed on the carbonate rocks. The browns and purples are kind of
confining. You need some basement rocks that interrupt the flow in the
carbonate rock systems. And then, the yellow is the valley field and
this is where a lot of the actually well development and pumping and
actually a lot of our head observations are centered in because that\'s
where the people live and it\'s an easy place to get some water.

You start to fill in the model and you look at it from the land surface
and you get kind of a different perception of what\'s in the model and
it looks like there\'s a lot more valley field than there is. If you
looked down below the surface, you see there\'s not as much connective
valley fields as it looked like on the land surface. So, this has been
very important in forming the framework for the groundwater flow model.

So, you have all this complex geology. Does this demand a complex flow
model? And, there\'s a lot of questions back and forth whether or not
this is, in reality, true. A number of the regional models we\'ve done,
so far, indicate that the complexity in the Death Valley region is
required. Most of this is because of the structural controls and the
scale of the geologic features in the Death Valley region. Large faults
with over 3,000 meters of flow on them requires some pretty detailed
geology to put the blocks in the system and have the spring flow
represented property. So, that was the reason we put together the
detailed framework.

This is kind of switching gears a little bit and talking about the tasks
that we\'ve been going through in the last year. As a number of you
realize, two main players in this project left in the last year and we
still have to put together a large transient model and a report and have
it published by the end of September. So, what\'s been going on in the
last year is putting together all the datasets and having them
published. All the supporting datasets are published and out. What
we\'re working on now is the transient model report. It\'s been through
review. It\'s had probably about every other month a kind of group of
people get together that includes the National Park Service,
representatives from DOE. Different interested parties have been looking
at the model as it\'s been being built which has made a big difference
during the review processes. We\'ve had comments all the way along and
tried to incorporate that information all the way along which has been
frustrating at times, but it\'s also, I think, made it a better product
in the long-run. The report went to review. Those people who were
reviewers, as well as a lot of internal survey people, reviewed the
model. We\'ve gotten reviews back and we have to have the report with
all the review comments responded to by March 31st which is in three
weeks. The model is transient. It represents a lot of the things that
the Park Service was interested in in terms of boundary conditions which
is a big change in the model. It also represents a lot of details on the
test site that weren\'t incorporated in terms of the geology and the
volcanics in the last few models. So, in order to be published and bound
and handed out on September 30th, it goes to the editor on March 31st.

Incorporated in building that model, there\'s a number of additions to
MODFLOW that were made, most of which are related to the hydrogeologic
units and incorporating like depth decay properties, decreasing the
permeability with depth, and ways of incorporating geologic information
into MODFLOW which has been nice for the community-at-large, as well as
made a much better model in this case. We worked a lot about model
consistency and trying to make some of the framework issues more
consistent at both the test site models and at Yucca Mountain. Mostly,
in this case, identifying areas where we need to work on that. Done some
work with predictive capability and some decision analysis tools which
I\'ll talk a little bit more about later.

The report is going to be in six parts plus two appendices. The
appendices include some regional boundary water budget type information,
as well as a regional potentiometric surface. There\'s various authors
on different parts. It\'s an introduction, then kind of a geology
chapter, kind of a conceptual model of the system. Kind of an
evaluations\--kind of a put-together of all the data that\'s supporting
the model is Part D. The framework which is kind of the synthesizing of
the geology and simplifying it to something we can get into the flow
model and then the actual text on the flow model.

Here\'s some details on the model. A lot of it will look very similar to
the older versions of the model. It still has a 1500 meter grid spacing
which leads to 194 columns and 160 rows. This is a satellite image of
the area. Spring Mountains are in here, Yucca Mountain is right in here.
You can see Red Cone and Black Cone from Crater Flat, the Amargosa
Desert, and Death Valley.

This grid across the model is the one and a half kilometer spacings of
the model grid. It\'s 16 layers. The top of the model now goes to land
surface, but this upper layer is convertible now. So, it can dry out and
receive water. It\'s wet-dry and it represents an unconfined condition
which was one of DOE\'s concerns at one point with the model before
being all confined. The layers have changed. Most of them follow the
water table except those upper layers in order to represent that drying
system.

The discharge is represented by drains which I\'ll talk a little bit
more about in the middle. The recharge is based on infiltration model
that Alan talked somewhat about. It\'s a transient simulation, as I
mentioned before. The first stress period is a steady state and it
replaces the 2002 steady state published model that was kind of a hard
merge between the two existing models.

This just shows some of the representation of the discharge by drains.
There\'s quite a bit of data constraining the model that\'s from spring
flow and evapotranspiration studies in the area which is kind of unique
for a groundwater flow model. Most of the models are constrained mostly
by head observations. So, we have head observations, as well as
discharge, constraining the model.

And, the way this dataset was put together, it was a lot of satellite
imagery was interpreted to get vegetation types. We had actual ET
stations out in the field to measure the rate of evapotranspiration at
the sites and then these areas were\--the numbers collected from the
field and the satellite imagery were put together to determine the rate
of evapotranspiration in each model cell. Then, that was used as a
calibration target and then the area of each vegetation type within each
model. So, it was used to come up with that

rate.

Recharge is based on Joe Hevesi and work Alan Flint have done on
infiltration model. This is the work that was published in 2003 with Joe
is the senior author. This is the infiltration model that was put into
the model. Higher infiltration which we\'re assuming basically simulates
as equivalent to recharge. High in the mountain ranges that are very
permeable like the Spring Mountains and the Sheep Range. One thing
that\'s different about this model than other infiltration and recharge
we\'ve used is there\'s focused infiltration in some of the channels.
You can see Fortymile Wash here in kind of a blue. And, that\'s a big
difference in matching some of the head levels, especially like UE-29,
A-1 and A-2, up Fortymile Wash. People are familiar with it.

One of the things we did to help calibrate it was to split the
infiltration areas into zones based on high- permeability rocks and
infiltration rates. So, if you had high-permeability and high
infiltration rates, we made one zone which is kind of this yellow color.
If you had volcanic rock and a moderate infiltration rate, you\'ve got
another color. So, we had these nine different zones and we used those
to form a multiplier times the infiltration rate to help calibrate the
model and that worked pretty well. The range in change between the
actual infiltration rate that was given in Joe\'s model and what we\'re
using in the model ranges from 85 percent of what the infiltration rate
is to about 115, 120 percent. So, it works pretty well, just some little
tweaking and moving things around.

One of the other constraining factors on the model is the hydraulic head
observations. We\'ve classified the data into kind of three categories.
Kind of steady state which represents no kind of change in water levels
based on human changes in the last, you know, 100 years, and those are
shown in yellow on this map. And, that was what was used basically to
constrain models in the past. There\'s also some transient data where
the head observations only represent changes\--represent having some
pumping effects in their observations and those were hard to use in the
past because we were trying to represent steady state conditions. Then,
there\'s wells that have both transient and steady state information and
those are shown in red.

So, there\'s quite a few points that just have transient information,
and by going to a transient model, we were able to incorporate that
information and it\'s helped constrain the model quite a bit which if
you look at the distribution of these wells, it\'s kind of telling of
where drilling is. It\'s just the Pahrump Valley, Amargosa Desert, and
then you have a lot of data out on the Nevada Test Site area, Yucca
Mountain in particular right in here.

Here\'s some of the transient information and the distribution of wells
in the model. It\'s the same satellite imagery kind of zoomed in. The
pumping was combined into one well per cell. The highest pumping rates
down in Pahrump and the Amargosa Desert, there is some pumping
represented on the test site. If you look at the change in pumping over
time, early-on wells were pretty deep in Pahrump Valley pumped from
basically Layer 4. As you go on with time with more and more pumping, it
is increased. There were some changes in the later time periods where we
just had some spikes and some decreases and changes.

One of the ways we looked at the calibration over time is to look at the
head observations and the residuals to see how well the model was
matching. Green dots represent pretty good matches, and as you get more
towards the warmer or redder colors, the observations don\'t match the
calibration as well. We also looked at the changes in the water levels
with depth. In blue here is shown the contours from the upper layer of
the model and red is the contours of, I think, Layer 16 in the model.
So, we used the GIS and going back and forth in and out of the model
helped calibrate it. It made a great deal of difference. We also looked
at a lot of the drain data. In brown is where it is simulated, too low
discharge and yellow is too high. So, we have a mixture of both of
those. So, we\'re matching both the evapotranspiration data and the
spring flow rates.

We\'re also looking at hydrochemical data more as kind of a qualitative
basis instead of looking at actually doing hydrochemical modeling.
There\'s some chemistry data that indicates flow needs to be coming from
this direction or that direction and Gary Patterson talks some about
that. The model tends to do okay with some of that. We\'ve looked at
some of the stuff with Ash Meadows and where flow paths are coming from
Ash Meadows.

If you start to compare this model to the 2002 steady state model that
was published, there\'s a much better match to the flows which are the
evapotranspiration and spring flow. There\'s many more head observations
which I pointed out and the bias and the match is a lot less. We have
some that are high and some are low and it\'s not skewed as much as the
previous model. The boundary conditions have been a huge change in this
model and we\'ve quantified the amount of flux coming in and out of the
boundary based on water budget studies. Jim Herrill and Doug Bedinger
looked a lot at that information and how much flow needed to come in
from like Saline in Eureka Valley and Panament Valley (phonetic) to
support water budgets in those adjacent basins. One of the big
contentions in that study is looking at the Sheep Range and flow going
in and out of there. Probably the biggest difference and the most
painful during calibration was converting the upper model layer to a
convertible layer and converting it to a transient model.

So, it\'s a regional model. It\'s good for answering regional type
questions. It\'s not meant to look at super site-specific type questions
and that\'s what site models are more geared toward doing. People are
going to talk more about site models. Some examples of things that it\'s
planned to be used for and is being used for are boundary conditions for
site-scale type models, both on the test site and at Yucca Mountain.
Looking at pumping scenarios by managers with decrease in spring
discharge based on pumping in the region. Looking at changes in water
levels based on pumping over time. There\'s been some talk about using
it for climate change and having it transient and going to land surface
will help a lot in trying to do that as a possibility. But, we need the
more site-specific models to address the more detailed concerns.

I was asked to try and talk a little bit about how the fluxes into the
site-scale model at Yucca Mountain have changed over time. This is kind
of the three models I\'m most familiar with. So, I\'ve put the flow
rates in and out of the sides of the site-scale model on here. This
black box represents the sides of this Yucca Mountain site-scale model.
In blue is the first three layer regional model that Frank D\'Agnese and
others put together about seven or eight years ago. In green is the 2002
steady state model. And, in red is a model run from a couple of weeks
ago from the transient model. The arrows are scaled by the values that
are in the table for the flow rates coming in and out of the side of the
model. It\'s pretty similar on the north. It hasn\'t changed a lot.
It\'s probably the area we know the least about. We don\'t really know
how much flux is coming down from the north. There\'s a pretty good
change on the west and south side representing how much flux is coming
in and out of the western boundary along the Amargosa River channel. In
the 2002 model, the flux for that entire west side was out. And, in this
model, there\'s more flux coming in representing that flow down the
Amargosa River area.

One of the changes that affects the south and this east is the
structures down here in the Specter Range and all the thrust faulting
and broken and shattered carbonate rock and how much is coming through
that. Depending on how you calibrate the regional model is where that
flux actually comes through. I think we had a lot more flux than we
needed to coming through that seven years ago and I think we\'ve scaled
it back. The amount coming out itself now is in between the two models.

One of the things about this model is it\'s supposed to be more than
just a model. The Deliverable is a report on the model, but it needs to
be a model that others can use and put together. Part of the way we
built this model was to have a geographic information system in a system
internally kind of called GeoPro that stores the model and makes it more
useful to other people. All the data is stored in geographic information
system format, basically ArcInfo and World Coordinates. We have some
analysis and visualization tools that should make it easier for people
to go use the data in and out of the model.

Part of the task for this year when we transfer the model over to DOE is
to have the supporting databases and this geographic information data as
part of the package. So, it\'s relying heavily on GIS and access to this
information. There\'s some custom tools that are GIS based and there\'s
also some 3-D model data like Earth Vision and Strata Model that will
not be perfectly usable by everybody in the world, but if you have those
tools, at least, you can use the files. So, a lot of the data is loaded
in kind of commercial software, especially the framework data, which it
was built in Strata Model, but we\'re funding this year to convert it
into Earth Vision which make it easier for the community-at-large.

What we\'re looking at doing right now in some of the out-year funding
and in some of the science and technology funding is local grid
refinement to facilitate coordinating between the more site-scale models
and the CAU unit models. Mary Hill has been doing a lot of research in
this area about more integration of the head and flow data between the
models so there is not as much of a hard just taking flux data back and
forth.

We\'re also looking at new methods to rank the importance of new
observations and monitoring both for geologic and head observations and
seeing if\--like if you drill a well here and get this water level, do
you need to recalibrate the model? Does it have enough information to it
that we need to recalibrate the model or is it just kind of supporting
what we have now? Methods to kind of look at the framework model and the
importance of the geologic information and how much is that actually
going to change the flow model as opposed to putting all that
information in and having to recalibrate it just to find out.

So, that\'s kind of the directions we\'re going and kind of a summary of
where the model is now.

NELSON: Thank you very much.

Let me just ask you straight out. Nelson, Board. In the model, will you
include the characterization of uncertainty, at all, linked to your grid
system? Will there be some evaluation of that or is it just going to be
the overall model that is made available?

FAUNT: It\'s built with MODFLOW-2000 and with parameter estimation and
some like composite scale sensitivity information built into it that
way. The way it\'s set up now, there\'s not like an uncertainty analysis
in the middle of the report. There\'s some of that information that\'s
built into the statistics that MODFLOW-2000 generates. We talked about
maybe next year doing some more details on actual uncertainties.

NELSON: Thank you. Nelson, Board. Just one other thing. Do you include
an upward flux out of the paleozoic limestones in this model in some
areas?

FAUNT: The base of the model is like 4,000 meters below sea level and
includes most of the carbonate aquifer system and down to a depth where
we don\'t think there\'s going to be upward flux. But, if you look at
like the flux in the carbonates to the volcanics in some areas there\'s
an upward flux and then you get up to the north of the test site and
there\'s a downward flux. At Yucca Mountain right now, we simulate an
upward flux from the carbonates into the volcanics.

NELSON: Thanks.

Okay. Thure?

CERLING: Cerling, Board. If you could go to Slide 19, I was just
wondering on some of your changes in directions of arrows and the size
of the magnitudes of the arrows, what information was the most critical
in causing both directions in values to change?

FAUNT: A lot of new data gathered by Nye County along that southern end
of Yucca Mountain, I think helped define the extent of the volcanics and
that\'s a big change between\--the blue, green arrows both were pre-Nye
County data basically and the red was just a transient model that
incorporates that data. I think that made a big difference on the extent
of the volcanics and where we had them in the model and the new
interpretations for the structures down in the carbonate rocks and how
we had the carbonate rocks. And then, also, I think matching the\--they
had some problems matching the discharge or we had some problems
matching the discharge in the 2002 model. I think with the better
matches in the discharge in the Amargosa area, that\'s what caused this
reversal in the 2002 model and actually the \'97 model matched some of
these discharge areas better than the 2002 model. I think that\'s why
you\'ve got the correct flow in this valley in here.

CERLING: Well, and I guess then as a followon to firm up your final
numbers, what areas do you think you\'re missing key information?

FAUNT: Let\'s see, some new information helps, some new information
doesn\'t do a lot of good, and a lot of times you don\'t know until
you\'ve drilled a well whether it\'s going to help you or not. It\'s
kind of a hard question to answer. We don\'t know a lot with depth. If
you start to look at these wells, they\'re mostly shallow. They mostly
go like 100 meters below the water table and that\'s it and then we\'re
trying to represent a deep system here which we\'re guessing based on
geophysics and a geologist\'s interpretation what the distribution of
the carbonate rock aquifer looks like below the land surface and how
deep these basins are. The depth of basins are based on gravity data.
Where we have wells that go through the entire sedimentary package down
to basement, sometimes they match and sometimes they don\'t. What
they\'ve done is adjusted the gravity to make a better model to make it
match better. And so, the more points we have that go deeper and help
constrain some of the basement information will constrain this model
better mainly because the main feature represented in this is the
carbonate rock aquifer with the volcanics in the alluvium as a smaller
system that this carbonate aquifer kind of constrains to a certain
extent.

NELSON: Okay. We have plenty of time. So, I want everyone to think up
questions. Claudia talked too fast.

So, next, Dan Bullen?

BULLEN: Bullen, Board. Actually, as a non-hydrogeologist, first, my
compliments on explaining a very complex model in simple enough terms
for me to understand. But then, that also raises the issue I can ask
questions about stuff that I don\'t quite understand.

In fact, I\'m glad we\'re at Figure 19 because I kind of want to get an
understanding of the respect for the magnitude of the arrows and maybe
an understanding of is there a conservation of mass within the system,
specifically with respect to water? The reason I\'m asking that is
because if you did incorporate a climate change and you had more
infiltration or more flux coming in from each of the surfaces and you
wanted to represent the groundwater table rise below Yucca Mountain, is
this the type of capability or the type of inputs that you would need to
do that? And then, the followon question to that is that you measured
from the north. There seemed to be maybe a dearth of data and would that
be an area where you\'d like to gain more information with respect to
this conservation of mass?

FAUNT: Okay. Let\'s see if I can remember all of these. The conservation
of mass, the MODFLOW does a conservation of mass and the regional model
has a conservation of mass and it has an error balance, I think, of .2
percent right now.

BULLEN: Okay.

FAUNT: In terms of climate change, you\'d have to get new recharge and
new discharge information and a sense of like paleo lakes and paleo
discharge deposits and some kind of \"estimate\" of how much water was
coming out those different parts of the system. You can do some of that
based on paleo information. I think Jim Paces will talk about it a
little bit or did talk about it a little bit. He talked yesterday,
right? Some of those numbers are hard to quantify. There are like Lake
Manley (phonetic), there\'s lake level stands in Death Valley, and you
can use some of that.

Grady O\'Brien and Frank D\'Agnese and I put together a model in 1999
that was a very simple model trying to represent climate change just by
increasing recharge and trying to match lake levels and paleo discharge
deposits. That model had some problems because it was a steady state
model and we ended up with lakes on tops of mountains and things like
that. The convertible layers on this would help solve some of that
problem. The more data you have, sometimes the better it is to build a
model; sometimes, it\'s harder.

I think the way this is set up, it yields itself to climate change
better because it\'s already set up for transient and also because it
has the convertible layers on top. It\'s just the data issue and it
would take time to put together all those datasets and where does
recharge change and by how much and is it going to be focused more in
the streams or do we need to incorporate a river package now? The
Amargosa which is ephemeral now, is that actually going to be a flowing
river at all times and be a perennial stream? The same thing with Salt
Creek in northern Death Valley. So, there\'s a lot of things to look at
and it\'s not going to be like a five minute turn-the-crank and it would
be representing climate change. There\'s a lot of details.

BULLEN: Bullen, Board. Actually, I appreciate that and I also appreciate
the candor of your answer because I think it is difficult to do the
kinds of calculations that are necessary.

You did make one comment with respect to infiltration and recharge. And,
in this model, did the recharge essentially equal the infiltration or
were there other losses in the infiltration that didn\'t necessarily
make it all the way down to recharge?

FAUNT: We didn\'t\--what we took was the infiltration model and then we
made these multipliers that were either like\--they ranged from like .84
to 1.18, I think, in the current version right now. That may not be the
final figure in the final model, the fraction of that infiltration, more
or less, that went into the model. In some areas, we had to increase the
infiltration rate that the infiltration model\-- which increased the
recharge which we\'re using the infiltration model. We didn\'t do
anything to redistribute it. At one point, I did some averaging and
spatially distributing it out and it actually matches better if we keep
the recharge rate where the infiltration model is.

One thing we have done in a couple places where we have some really
tight rocks near the land surface in the framework and we\'re getting
ponding of recharge, we basically zeroed out the infiltration rate or
made it very small in those areas and increased the rate around the
edges of those cells. So, that helped redistribute it a little bit. So,
it was a little bit of redistributing only where we had really tight
rocks and we were getting this mounding effect.

BULLEN: Thank you.

NELSON: Parizek?

PARIZEK: Parizek, Board. On this particular figure, would you go so far
as to say that you could do more work on just the fluxes? As one of the
things, if you had to have new data, obviously not one drill hole, but
if you were trying to confirm the red arrow to the south or any of the
arrows to kind of build confidence, would that be a worthwhile cause?

FAUNT: Sure, I think you\'d also spend more time looking at
hydrochemical data and seeing like if the hydrochemical data\--I know
Gary\'s talked about the compartmentalization nature of the flow system
and different chemical signatures in different areas. If you start to
look at that to make sure where the fluxes are going are matching some
of that hydrochemical data, that might add to some more certainty in
this. This is a composite of the entire side of the model. You could
start looking at the variations with depth and maybe like the variations
of the flux coming in through the carbonate versus the volcanics in the
alluvium in the system. I haven\'t done that, at all. I, quick and
dirty, did this one afternoon after it was requested that I kind of put
this together summarizing it.

I mean, yeah, there\'s a lot of work you could do with that and I think
you probably could get a better understanding of the system and maybe a
better understanding of some of the limitations to how things are
represented because you have to remember it\'s one and a half kilometer
spacing so it\'s\--I think, it\'s 20 by 30 cells.

PARIZEK: Right. Parizek, Board. And then, also, what happens in the
Funeral Mountains, the next speaker will give us more insight about that
and that may help constrain it further. So, these are the kind of
experiments that can give you additional value.

FAUNT: Yeah.

PARIZEK: Figure 16 shows the pumping distribution. Now, if you look at
the Pahrump area, there\'s an awful lot of water coming out of the
system. Do you put any of that water back in or is it all consumed by
your model? You assume you consume it. Where is\--is a lot of that
sewage affluent going back into septic tanks?

FAUNT: We didn\'t look a lot at like return flow. The pumping rates that
Randy put together assumed a little bit of return flow in them so that
the amount of pumping was decreased by a fraction to kind of quasi
include return flow, but we didn\'t do a lot in detail with it. Partly
timing and partly what we were able to simulate with the system, the
data isn\'t detailed enough to\--

PARIZEK: But, it is partially captured by\--

FAUNT: It\'s partially captured.

PARIZEK: What about springs? Like the Ash Meadows area and elsewhere,
again there\'s a high evapotranspiration loss, but I\'m sure some of
that water probably reenters the groundwater system. Have you been able
to put any limits on that or estimations or does the model consider
that?

FAUNT: Randy Laczniak would be a much better person to answer this, but
what he did when he calculated the evapotranspiration in the spring flow
rate, he looked at the fact that you\'ve got these springs flowing out
and a lot of evaporation is actually from spring flow. And, I can\'t
remember if he decreased the spring flow rate or decreased the
evapotranspiration rate to take that into consideration, but it was
thought about in the process of determining those discharge areas. The
way those drains are set up is most of them are in Layer 1 representing
evapotranspiration, but where there was significant flux from a spring
and it was warm temperature so it was thought to represent the regional
system, the actual drain location was put at the top of the carbonate
system to represent flux out of the carbonate aquifer.

PARIZEK: Parizek, Board. How faults may have been handled\--say,
principal faults or something that you might really think have
hydrologic significance more so than others, can you give us some idea
how that was done?

FAUNT: Uh-huh. Some of the faults act as conduits and some act as
barriers and some act as both. The way they were explicitly put into the
flow system and into the model was as barriers using the hydrological
flow barrier package, HFB package. This model didn\'t need as many of
those barriers as other models because I think the juxtaposition of the
units was represented more accurately so you could have the low K rocks
juxtaposed against the higher K rocks and that juxtaposition causes a
lot of the discharge. A few of the barriers were needed and those seem
to represent faults that have like a core of impermeable material from
like the basically Las Vegas Valley sheer zone is a good example of that
where you have like probably some low-permeability material fault gouge
that\'s actually blocking the flow in the actual structure.

The carbon aquifer\--actually, almost all the aquifers were zoned based
on their structural province they were located in and how fractured or
shattered they are and like whether they\'re coarse-grained or
fine-grained. So, they\'re kind of highly faulted, highly shattered.
Carbonate rocks tend to be very permeable rocks and those were
represented as zones in the carbonate aquifer. So, in a way, structures
are represented that way by like kind of a shattered zone in the
carbonate. So, those would be kind of more conduits. Those were very
important in the carbonate system especially\--and in some of the
volcanics\--to kind of be kind of conduits to flow. The location of the
Eolian and the clastic confining units kind of controls the flow system
and those barriers and where those are in the framework model so
structures kind of that way are important.

So, they\'re kind of represented partially by the framework model which
has the juxtaposition of the units, partially by flow barriers which
actually act as a linear barrier between model cells and represent a
fault, and then partially by the zonation of the different aquifers and
confining units in the model.

PARIZEK: Parizek, Board. So, when you say some faults have both roles,
it might depend upon the depth of that particular fault where it\'s
serving one role in another part along the line or another depth
position would have another role, but not both roles at the same
location. Do you have any field evidence where you could have damming
effects, say, on a foot wall and maybe shattering on the hanging wall
and, as a result, have both a drain and a damming effect on the same
fault in the same horizon or same hydro structure unit?

FAUNT: There\'s some data like lower carbonate aquifer when it\'s in the
upper thrust plate, it\'s been shattered more and it would have a higher
permeability. And, that was put in as like a zone. And then, that zone
happened to abut against a flow barrier which it probably does down in
the Las Vegas Valley sheer zone. You kind of have that situation, but
it\'s not represented explicitly like that.

PARIZEK: Parizek, Board. One more question about now having gone to the
transient model, you\'ve obviously had to do a lot of things to
calibrate it using transient data in different parts of the model
domain. If you then go back to a steady state model, say, back for
program use, that\'s a better model as a result of having gone through
this transient model?

FAUNT: I think so.

PARIZEK: Can you give some sense of improvement, how much better
improved it is?

FAUNT: There are a lot more different ways you could represent the
alluvium and basin fill deposits, basically the fine-grained and
coarse-grained gravels and sands and clays. With just the steady state
data, you could get very different hydraulic conductivity values in
those units, in particular. And then, when we put the transient data and
you put in the pumping, that really constrains and limits those values
and it made a much better separation between the conductivity values
between those aquifers and confining units. So, I think, in that way, it
helps improve the data even in the steady state model. I think that\'s
partially what helped improve matching the spring flows and the drains
because most of those are located in the valley field deposits, as well,
as well as along structures.

PARIZEK: Thank you very much.

NELSON: Frank?

SCHWARTZ: Yes, hi, Schwartz. Claudia, one of the things I wanted to ask
you was the balance between recharge and discharge in the steady state
model. Obviously, they probably balance. Recharge seems to be something
that you define fairly rigorously and so probably, although you tuned it
a little bit, it sounds like the numbers you started with were sort of
fixed. Discharge, I understand, you determined sort of independently. I
mean, you have a model estimate, but you also have a sort of a field
estimate of discharge. The amount of discharge you actually get out of
the model, when you first came up with your independent discharge
estimates, field estimates, I mean, how close were they? Did they match
or was there a discrepancy and you kind of said, well, we\'ve got to
find some more discharge here and went back out there in the field and
looked? I mean, how well did the discharge actually match your best
estimate of recharge?

FAUNT: It matched pretty well. A lot of care was taken to make sure that
the discharge rates weren\'t affected by pumping that we were trying to
establish. We actually went back and took old reports where there was
photos and distribution of freataphytes (phonetic) in the past and used
those to distribute the amount of evapotranspiration areas in Pahrump,
in specific. We did have problems matching discharge in Death Valley and
Pahrump. Actually, during the last year and a half, the amount of
discharge estimated from Death Valley doubled from what their initial
estimate was. And, the amount in Pahrump changed by a factor of a third
and I can\'t remember if it went up or down. Most of the pumping

\--and I thought the pumping would be a relatively small feature in this
system and not a large amount of volume, but the amount of pumping
actually ends up being about a little over a third of the amount of
discharge coming out of the system. It\'s a lot of water coming out of
this system from pumping. Most of that is coming out of storage, but
there\'s a lot of water that\'s been taken out of this system by
pumping.

SCHWARTZ: Because where I guess I was going with the question was
looking at the whole problem of uniqueness of a model of this kind. And,
clearly, if recharge and discharge are not too constrained, I mean, you
can make them anything and just adjust Ks and, you know, the model will
give you the same head distributions. So, do you feel confident that
that\'s your major proof that\--or tendency toward uniqueness is this
balance between recharge and discharge or are there other things, as
well, that you think that would let you sort of believe that this is the
unique model?

FAUNT: I think, the fact that the boundary conditions change so
significantly, they didn\'t affect the internal part of the system very
much. It helps constrain that it\'s somewhat of a separate area in the
internal parts. A lot of work went into those evapotranspiration and
spring flow studies and putting together that information. In general,
models don\'t tend to have that much discharge information to calibrate
to. And, the fact that like, especially in Pahrump, we have changes in
discharge over time where the springs actually dry up and then start
flowing again and we tend to match that with the pumping data, I think
that helps constrain it a lot. I think the fact that we have head
observations in multiple layers where you have gradients upwards and
downwards, I think it makes it a lot more unique, especially adding the
transient data and the discharge changing over time. Pahrump is the only
place we actually have data where the discharge from the ET areas is
changing over time, where we have an estimate of what we thought it was
before development and we have a development estimate and then we have
where they decreased the pumping and springs started flowing again and
trying to simulate that change. We don\'t match the actual magnitudes
exactly, but we match the kind of general trends. And, I think that\'s
encouraging.

SCHWARTZ: Good, thank you.

NELSON: And, van Genuchten?

VAN GENUCHTEN: Yeah, van Genuchten. I was intrigued by your Slide 20.
You know, I don\'t know if we can get that, but I\'m sure in this
impressive study, you guys put a lot of time and effort and sweat and
tears in this and you want to get some credit out of this also. So, I
can understand you want to protect all the stuff you developed. But, at
the same time, you hint here, you call it knowledge exchange, that some
of the data may be available in commercial software. Personally, I think
it\'s great because we have this available in the wider scientific
community and all the people kind of scrutinize and use or may misuse
whatever you developed. Could you comment on that? Is there a certain
company or how do you do this and is it expensive? It is going to break
the bank for us to get this?

FAUNT: We worked hard at trying to find ways to transfer the data in
less expensive systems. Most of the data is stored in ArcInfo types of
grids. All the model information that goes in and out of the model
actually is stored in either ASCII tables or ASCII arrays for MODFLOW
input. And, also, those representations are stored in ArcInfo grids,
arrays, Vectra coverages or Point coverages, and also like Access
database tables. So, Microsoft Access is relatively cheap. Probably,
we\'ll release the GIS data, shape files, as well as grids. A lot of
software can read that. So, depending on what software you have, you can
look at that.

The kind of sticking point with releasing of the data is kind of the 3-D
geology data and how you represent that and how you give that to
somebody. It can have arrays with thicknesses and tops of units and it
can be used or misused or represented correctly or not. Even going from
Strata Model to Earth Vision which are two 3-D geological modeling
packages, they\'re very high end, they\'re very expensive. They\'re
built originally by\--one is (inaudible) Industry and one is kind of
environmental. They are tens of thousands of dollars. They even don\'t
communicate exactly the same and you can\'t just take the arrays and
plot them out of Strata Model and plot them into Earth Vision and have
the same looking model. We have the arrays represented in MODFLOW and
putting those into Rock Ware which is a relatively inexpensive
visualization package. And so, we\'re releasing the framework model that
way. The graphics aren\'t as pretty as Earth Vision, but the data is
there and you can look at it to a certain extent. So, that\'s the one
that probably has the biggest sticking point of how accurately you
accurately want to represent the 3-D geology data.

Actually, the geological arrays are in ArcInfo. You can use ArcScene
which is kind of a pseudo 3-D thing and look at the geology in it. And,
I actually spent a lot of time re-representing the geology in ArcInfo so
other people could look at it easier and you can put basically the
equivalent to a well in each cell and then you can see the geology in
each cell by clicking on it and stretching it and making the unit
stretch to the thickness. So, there\'s tricks and ways of getting it out
and looking at it in relatively inexpensive software. A lot of it is
hinged around ArcInfo and ArcInfo isn\'t cheap, but it seems to be a
pretty big standard and a lot of people have access to it.

NELSON: One last thing. Nelson, Board. Well, just following up, I think
you may find in the future open source capabilities here that happen
very fast, I think, within the next year. So, it would be really great
to try to get this available through open source. To what extent did you
use any information, thermal information, in this model?

FAUNT: We haven\'t used temperature data hardly, at all. I mean, there
was talk originally about trying to do it and we haven\'t done it. There
was a lot more of starting to look at it with the site model and I think
someone is going to talk about the site model later. I\'m not sure how
much\--I haven\'t been involved with that enough to know how much it was
incorporated. I mean, qualitatively, we looked at it in terms of the
spring discharge and figuring out which were regional springs, but
we\'re not representing it as part of the flow system.

NELSON: Nelson, Board. That would be one area that there is information
that\'s not yet been captured.

FAUNT: That\'s true.

NELSON: Okay. And, just finally, does your model tell you anything about
the style of faults\' behavior hydrologically in the tertiary volcanics?
Are they typically permeable, impermeable, or is there anything typical
about them?

FAUNT: Nothing is typical in those volcanics. The welded rocks where
they\'re shattered tended to behave more as aquifers. We did a pretty
detailed kind of like gridding of like where things were altered or
non-altered by zeolitization, where rocks were welded versus nonwelded,
and made categories and zonations based on that. In general, the welded,
shattered areas tended to be more aquifers and higher permeability and
the altered, nonwelded rocks tended to be more of the confining units
and lower permeability. And, that actually was more true that those
properties controlled the flow more so than the unit. Like the Calico
Hills formation is one formation, but it was definitely an aquifer in
some areas and a confining unit in other areas. That was based more on
the properties. I know Dave Bush is going to be on the field trip and
probably talk some about that and I\'ve talked with him in the past
about this may not be the unit so much, but the properties of the units
that are the actual factors that control the permeability.

NELSON: Thank you very much.

FAUNT: Sure.

NELSON: Thank you, Claudia.

We\'re on schedule, at least, by my clock. So, our next speaker is Dr.
John Bredehoeft and he is an extremely well-known researcher and
scientist. He accumulated 32 years of service in the USGS where he held
both research and management positions and his expertise is in water
resources, especially regarding groundwater. He\'s testified before
Congress on issues from national policy to the use of numerical models
and management decisions. He\'s served on many National Academy and
National Research Council committees and panels. He, himself, is a
member of the National Academy of Engineers and he has received numerous
prestigious awards. In 1995, having retired from USGS, Dr. Bredehoeft
established the Hydrodynamics Group. One of the projects of this group
with Inyo County is what he will be talking about today.

Welcome, Dr. Bredehoeft.

BREDEHOEFT: Thank you. Thank you very much.

As you said, my partner and I have been engaged for Inyo County as their
oversight consultant almost for eight or nine years at this point in
time. And, I want to talk about Inyo County\'s concerns, but before I do
that, I want to make a few philosophical remarks about the whole issue
of modeling and what we\'re doing.

If I have some claim to fame, part of it is due to the fact that George
Pinder and I developed the first widely used flow models and the first
widely used contaminant transport models for the saturated zone. And, we
did that in approximately 1970. So, we\'ve been engaged in the modeling
business\--I\'ve been engaged in it for more than 30 years. So, it\'s
been one of my principal activities. And, I\'ve been concerned about the
whole idea of how we model and the idea of the philosophy of modeling
and I want to spend a few minutes just talking about that. As I do that,
I want to disassociate that from Inyo County. These are my ideas.
They\'re not in any way associated with the\--I mean, these are really
my ideas; Inyo County didn\'t pay for these activities and so, as I say,
they\'re my ideas.

Okay. Next slide, please? All right. So, about a year ago, I published a
paper in Ground Water which you can see the title there, \"From Models
to Performance Assessment; the Conceptualization Problem\", and that\'s
what I focused on, the conceptualization problem. Now, you know, the
whole basis for any modeling we do is the conceptual model. That
conceptual model is an a priori decision by the analyst. Now, the
analyst decides what the conceptual model is going to look like. And,
certainly, we say we have some ideas in science on what the prevailing
conceptual models are, and among those, you select what the conceptual
model for the particular problem is.

Now, as a result of that, certain things, it seems to me, happen and the
next slide is the result of the consequence of selecting the conceptual
model by the analyst. Now, these are the points that I made in that
earlier paper and I\'ll just read them off. One of the things is that
usually you select a conceptual model and you stick with it. So, once
you\'ve selected that conceptual model, that\'s generally the conceptual
model unless something else happens and I\'ll talk about that in a
minute. But, usually, the idea is that I\'ve got a conceptual model and
I\'m going to stick with it. Now, when you start to look at how well did
we do predicting with these models\--and I\'ll talk a little more about
that in a minute\--you find out that in many cases the errors associated
with the predictions are associated with, in fact, the selection of the
conceptual model itself. So, the errors result from the conceptual
model.

The next thing is that, more often than not, you can take your dataset
and fit it to your conceptual model. Whether the conceptual model is
right or not, you don\'t know, but more often than not, you find that
you can take the data that you have and fit it to the conceptual model
and now we have a lot of automated procedures to do that\--tests,
MODFLOW-P, various things\--which will reduce the error between the
observations and the model predictions and you get what you think is a
reasonably calibrated model. That doesn\'t mean just because I
calibrated it that I got the right conceptual model. All it means is I
got a good calibration.

All right. Now, the last thing is that these other things that we do in
PA which is probabilistic sampling of the parameter set does not assure
that you have tested the appropriate conceptual model. All you\'re
really doing is looking at the possibility that there are errors in the
parameter set itself. So, it doesn\'t mean that you have, in fact,
tested the conceptual model itself.

All right. Next slide, please? Now, as I said I published those ideas
about over a year ago in Ground Water and I got into a discussion with
Shlomo Neuman. Shlomo didn\'t disagree with my conclusions, but the
question is what do we do about it? How can we solve this conceptual
problem? So, Shlomo\'s idea is that what the analysts should do is, in
fact, set up a set of conceptual models, then look at the data, and try
to select among that set of conceptual models what is the appropriate
conceptual models or what is the appropriate set of conceptual models
for the particular problem? Now, if you follow along with Shlomo\'s
argument, it means that the analyst then has to set up this set of
conceptual models and the question that I asked is, you know, how good
are we at selecting this set of conceptual models, either the individual
conceptual model or a set of conceptual models? So, I tried to look at
the data that we have and the data is extremely sparse at how well we do
at setting up the conceptual model.

Now, this led me to another sort of philosophical discussion and that is
the whole idea of surprise. And, the idea is relatively simple. You have
a conceptual model. All of a sudden, you collect some more data and that
data says the conceptual model that we have is invalid. So, then you\'ve
got to go back and readjust your conceptual model and create a new
conceptual model. And, we all know that that happens. I mean, you start
with some idea. Alan Flint talked about Yucca Mountain yesterday and you
can see that this happened along the way at Yucca Mountain, but it
happens all the time, I think.

Now, probably looking at sort of what are these big surprises, you know,
the one in geology in the last century, in the 20th century, was plate
tectonics. You know, Alfred Wegner came along in 1912 and said the
continents are moving and the geologists said, no, no, no, that can\'t
be right. The continents can\'t move. And then, we came along in 1960
and we measured remnant magnetism on the ocean floor and we found these
stripes on the ocean floor. All of a sudden, we realized that there was
sea floor spreading at the oceanic ridges, and as a consequence of that,
the plates have got to move. So, you know, really what happened was you
had a conceptual model\--the conceptual model in this case was that the
continents can\'t move\--all of a sudden, you find this new data, and it
says, hey, wait a minute, the conceptual model is all wrong.

Now, as I said, we all are aware of those kinds of things which I\'m
calling a surprise in this case. And, you know, we think about these
things and we say to ourselves, well, they happened\--and big problems.
You know, they\'re big problems. We have big scientific problems, and
all of a sudden, people come along and get some new data and it throws
out the original hypothesis. The question is how often does that happen
sort of in the routine investigations that we\'re engaged in? Does it
happen and how frequently does it happen?

Now, my two examples sort of in the nuclear waste business is, first of
all, at WIPP, the idea\--let\'s back up. Why did we go to salt as sort
of the primary storage media? One of the reasons, at least, was there
was a National Academy committee in the 1950s in which there were very
prominent hydrologists. C.V. Theis and King Hubbert were both on the
panel. And, they said, you know, salt, that\'s the media of choice and
it\'s going to be dry. So, we\'ll put the radioactive waste in salt.
And, that was the conceptual model when we started on the WIPP site. You
know, the conception was that the salt at WIPP was dry. And, it wasn\'t
totally dry. It was known that there were vesicles in the salt and those
vesicles contained brine and there was about a half of one percent brine
in the vesicles. Everybody admitted that. However, we went underground
and, all of a sudden, we find that the mine is wet. Not wet, but it\'s,
at least, damp and, you know, you saw indications of this when you went
underground. The first real data we had was they ran a heater
experiment. Where they turned the heaters on, they circulated dry
nitrogen in the holes and, of course, the nitrogen came out wet. So, it
was immediately realized\--or, not immediately, it took some period of
time, that this conceptual model of dry salt was, in fact, not right;
that there was one to three percent brine in the interstices and that
brine would move to the repository and the repository would be damp, at
least; so, a new conceptual model.

And, I think, you see the same thing at Yucca Mountain. You go
underground and you find chlorine-36 and then, all of a sudden, you have
to say to yourself, well, there are fast paths and the fast paths
suggest that our conceptual model of what\'s going on in the unsaturated
zone is, in fact\--we\'ve got to throw it out\--it\'s invalid. We\'ve
got to create a new conceptual model of what goes on. So, these things
happen.

Next slide, please? So, I said to myself, all right, how frequently has
this happened in my own experience? So, I\'ve been consulting for
roughly nine years. I\'ve been involved with 21 model studies, more or
less. And, out of these model studies, I find that four to six times,
something of that order, we had to change the conceptual model. We
started with a given conceptual model and that conceptual model had to
be radically changed. And, it\'s not just that we have a new parameter
set, we\'ve got to change the conceptual model itself, not just change
the parameters.

That led me to say to myself, well, that\'s my experience. What is the
experience associated with post-audits? You know, we have been modeling
now for 30 years or so and the question is how well did the models do?
So, there have been, as you know, a series of post-audits to look at
what are the model predictions and how good were those model
predictions? And, the numbers of these are not very large, seven or
eight, something like that. It turns out the model predictions weren\'t
very good.

And, I went back to look at that information to say, okay, not just
where the parameters were changed, but where was the conceptual model
itself bad? Where did we have to really look and say to ourselves that
the errors in the predictions were associated with the conceptual model?
And, it turned out that\--you know, it turns out that 20 to 30 percent
of the time, the conceptual model itself was bad. So, my total dataset
then turns out to be 29 studies including my own. And, out of those, the
conceptual model was changed seven times significantly and then there
were another two or three that were questionable.

So, what it\'s suggesting is that we have trouble selecting an
appropriate conceptual model, at least, the first time around and that
many times the conceptual model\--oh, many times\--20 to 30 percent of
the time, the conceptual model we select is not the conceptual model we
end up with. Now, of course, we\'ve got this other three-quarters of the
studies where we accepted the conceptual model and we went ahead with
it. We don\'t know how many of those are wrong.

So, my point is that selecting the appropriate conceptual model is not
so easy and we make mistakes rather commonly. And, those mistakes, I
think, are often\--I mean, I go back again to my initial slide saying
that, you know, even with a bad conceptual model, you can calibrate this
thing. That doesn\'t mean that it\'s\--just because you calibrate it
doesn\'t mean you\'ve got the right conceptual model. So, this is a
difficult problem and I think it\'s a very sticky problem in modeling.

Next slide, please? So, I think I\'ve made those points that, you know,
my experience suggests that 25 to 30 percent of the time we have
problems. All right. So, it seems to me that this leads to uncertainty
and this kind of uncertainty is not covered in the sort of performance
assessment that we normally do. We look at the problems associated with
the parameters, but we don\'t look at the problems associated with the
conceptual model itself. All right. So, so much for philosophy.

Now, next slide, please? Some more comments about the idea of surprise,
and even though Shlomo was saying\--you know, even he admits that it\'s
not uncommon to find new data that says the conceptual model is wrong.

So, anyway, the next slide, please? All right. Now, getting on to Inyo
County and what are the concerns of Inyo County? As all of you know, the
lower carbonate aquifer is thought to discharge in Death Valley, into
the big springs in Death Valley. You know, if we get contaminants to the
lower carbonate aquifer, that\'s where the stuff is going, so Inyo
County is concerned about the discharge from the lower carbonate
aquifer. That\'s how it gets into Yucca Mountain really. So, what we
have been trying to do then is to look at the discharge area in more
detail in California, basically. And, basically, since most of it
happens in Death Valley, we\'re looking at the springs in Death Valley
and what happens to those springs.

All right. The next slide, please? Now, you\'re all familiar with this.
There\'s the test site. This facility is the closest and we end up with
these major springs in Death Valley.

Okay, next slide, please? Now, we have been supporting some work at the
USGS to map the carbonate aquifer in the Furnace Creek Mountains. And,
Chris Freidrich of the USGS has been doing that. And, so this is Chris\'
geologic map of the Funeral Mountains. And, you can see the carbonate
aquifer exists. The carbonate blocks are these pinkish blocks which
exist right in here. We don\'t see them too well from here. Okay. And,
there is\--these blocks are all faulted, and right in the center here,
the carbonate aquifer is actually faulted out. So, there\'s a big block
of carbonate sitting in here and then another block of carbonate which
exists in this area of the Funeral Mountains. So, Chris has mapped that
in fairly detailed\--as detailed as he can from the observation. What
happens is that since those blocks are faulted, you can only see certain
exposures of the fault. So, you\'ve got to project the fault into the
subsurface.

So, the next slide, please? So, there are different interpretations of
what the bottom of this fault zone would look like. So, as you can see
here, these are the carbonate blocks and they\'re faulted in here. So,
what Chris has done is prepared a contour map on the base of the
carbonate aquifer and this is that contour map on the base of the
carbonate aquifer. This is the Funeral Mountain Fault here along the
front of the Funeral Mountains. And, the major springs discharging are
the springs in this area here. The three big ones are Nevares, Texas,
and Travertine. Then, there are some smaller ones, two smaller ones up
here, and another one down here. And, you know, the reason we think
those springs are discharging from the carbonate aquifer is based on
their geochemistry. You know, it looks like carbonate water chemistry.

All right. So, this is Chris\' bottom of the aquifer and right in here
is this area that\'s cut out that\'s faulted out. So, we have an area in
here where there is no carbonate aquifer. This area right here, there\'s
no carbonate aquifer. And, when you look at this map, the elevation of
the bottom of the carbonate here is about 1600 feet above sea level, if
I\'m reading that correctly. I think that\'s a 1600 foot contour. So, we
have some information. We know that the springs here exist in this area.
We have a pretty good estimate of their discharge. They discharge
approximately 5 second/feet. Our best estimate is that it\'s 5
second/feet. And, we have some areas over in here where the Amargosa
River looks like it\'s very wet. There\'s vegetation along the Amargosa
River and it appears that there\'s discharge from the carbonate aquifer
to the Amargosa River. The elevations here are about 2200 feet. The
Devil\'s Hole which is back up in here has an elevation that\'s
somewhere between 2100 and 2200 feet. So, it looks like the head in the
carbonate aquifer is around 2200 feet in this area on the east side of
the Funeral Mountains. Okay. So, this is Chris\' bottom of the aquifer
with the sort of shallowest fault zone. In other words, you can only see
a portion of this fault zone. So, you project it into the subsurface and
you picture this plane as relatively low dipping. You get this bottom of
the aquifer.

Next one? And, this is another realization where you say to yourself,
well, these faults are a little steeper and when you make the faults
steeper, of course, you get a different bottom and the bottom here is
considerably deeper and we get sea level somewhere right around in here.
So, this area that we\'re concerned about right through here where most
of the water has to come through is considerably lower. So, instead of
the bottom being around 1600 feet, we\'re now about 500 to 1,000 feet
lower.

So, the next slide? So, what I did then is to say to ourselves, okay,
let\'s see if we can model the flow through the carbonate aquifer and
we\'re going to assume that, you know, it behaves at a continuum. You
know, we\'re not doing anything exotic. We\'re simply saying to
ourselves we\'ve got to use the general flow models and I used MODFLOW
actually to model the system. This is a model representation of flow
through the carbonate aquifer. It has a constant head boundary up here
along the Amargosa River and then we\'ve got these discharges of the
springs here and we know what the elevation of those springs is, as
well. So, we have some constraints on what the elevation of the springs
are and what their discharge is. From that information, we can put
together a model of the aquifer and compute a head distribution in the
aquifer.

Now, what\'s interesting about this is that right in here, the model
suggests that the elevation of the water table in the carbonate aquifer
would be about 1600 feet. So, what it\'s saying is that that shallow
realization that Chris put together is probably not, at all, feasible
because basically we\'re saying that there is no aquifer thickness in
here. The model is fairly interesting because you see all of the flow in
the carbonate aquifer has to come through this area and then come down
here to discharge in the big springs in this area. And, there is some
discharge right here, but it looks like there is discontinuity from the
carbonate aquifer. This spring is considerably higher. It\'s somewhere
around 2,000 feet. So, it appears to be pretty much disconnected. The
flow for that spring has to come sort of this pathway through here.

So, basically, what we\'ve done is put together this model of the
aquifer system. It suggests to us that, you know, this shallow
realization of the fault system is not really feasible and so it looks
like the faults are much steeper than Chris would have predicted with
his shallow fault model. And, we can fit this thing pretty well to the
discharge. I mean, we can make the model reproduce the discharge in the
major springs here, particularly, as I said, Travertine and Texas and
Nevares. So, the model does reasonably well.

Now, one of the interesting things is that this fault doesn\'t seem to
have very much effect. So, I played with the idea of, you know, suppose
the fault is more permeable, suppose it\'s less permeable. I didn\'t get
any better results with less or more permeable. So, it appears that the
fault is in this case playing no particular role in the flow system. The
flow is going basically through the fault zone.

All right. So, this leads then to what are we hoping to do? Well, we\'re
hoping to drill some holes to the carbonate aquifer over in this area
here. So, on the east side of the Funeral Mountains, we would like to
drill to the carbonate aquifer, get head information, geochemical
information, and establish the fact that the head that we get over here
is consistent with some kind of flow system that looks like this and
that the geochemistry of that water resembles the water that we\'re
seeing discharged at the springs. So, basically, establish\--well, get
some confirmation for our conceptual model of what the flow through the
carbonate aquifer looks like. We have money to drill. We are hung up
somewhat logistically by the contracting procedures in Inyo County. This
is a kind of new ball game for Inyo County and we are having some
logistical problems in getting the county to move, basically. We\'ve
also drilled some holes over here in the discharge area and we\'ve got
one monitoring well also in the discharge area. But, the more meaningful
observations, I think, are those of the carbonate and over in here and
we\'ve done geophysics to try to locate spots where we think we\--where
we\'re pretty sure we can get the carbonate aquifer, get saturation
within reasonable drilling depths. So, that\'s where we are.

The rest of the slides simply summarize that. You know, and I might make
one more comment. You know, because we have head distribution, we have
discharge from the springs, we can calculate a transmissivity of the
aquifer. Now, you\'re not quite sure what that transmissivity means
because you\'re not quite sure what the thickness of the aquifer
material is that\'s really transmitting the water. So, out of the full
modeling, we can get a transmissivity, but you know, converting that to
a permeability depends on how thick you think the aquifer material is
that is conducting the water. And, as I said, it\'s fairly insensitive
to the permeability of the Furnace Creek Fault.

I think I\'ll stop here. There\'s one or two more slides, but I think
I\'ve covered everything.

NELSON: Thank you very much.

Questions from the Board? Dan Bullen?

BULLEN: Bullen, Board. Could we got to Slide 13 first? I guess, the
first question that I have based on the initial part of your talk was
that this is your estimate of the movement of the groundwater. So, I
guess, I have to ask if you think it\'s correct, and if it\'s not
correct, where might it not be correct?

BREDEHOEFT: Well, let\'s back up a second. There is every indication
from the geochemistry of these springs that the water we\'re getting
from the springs is coming out of the carbonate aquifer. So then, you
say to yourself, okay, we\'ve mapped that carbonate and the distribution
of the carbonate is pretty well-known. So, you say to yourself, well,
there\'s carbonate water coming out of the springs and the water has got
to come through the Funeral Mountains. Then, this is a reasonable
picture of what that\'s got to look like and it\'s pretty hard to change
that thing dramatically.

Let me back up. One of the things I did in here was to put in the
uniform permeability for the carbonate\--or uniform transmissivity for
the carbonates through the entire Funeral Mountains. So, you could come
back and play games with making different permeability distributions or
different transmissivity distributions, but it seems to me you don\'t
have much data to do that with. So, you know, you come back and say to
yourself, well, what\'s the simplest model? Well, the simplest model is
to use a uniform transmissivity. The pictures kind of look something
like this, I think.

BULLEN: Bullen, Board. Basically, as a followup, on Figure 11, you show
the proposed wells that would go in that region and I guess I just
wondered why there weren\'t wells near where the spillway is? Would that
not give you the information that you need or is that too hard to get
or\--

BREDEHOEFT: It\'s pretty hard to get to, first of all.

BULLEN: Okay.

BREDEHOEFT: Then, there are logistical problems because you\'re right in
the center of the National Park. National Park doesn\'t want us
drilling. You know, they\'re not anxious for that, although we have
drilled some wells over in the discharge area. So, you come back and you
say to yourself, well, where can you get that carbonate, you know,
within reasonable drilling distance on the other side of the Funeral
Mountains on the northeast side. And, these are the sites. It turns out
that when you start looking at the logistics of where the park is, you
know, where is it possible to drill, it comes down to a fairly limited
set of places.

BULLEN: Bullen, Board. Thank you. Actually, I had one other question.
Based on the previous talk and trying to understand sort of the regional
nature of the groundwater motion, how does your information feed back
into the process or is there a mechanism whereby this information can be
utilized by either the GS or the Yucca Mountain Project and what kind of
information feedback do you have?

BREDEHOEFT: Well, particularly in the models that we did here, we were
looking only at the carbonate and we\'re looking at the carbonate, you
know, sort of this is the water table in the carbonate in the Funeral
Mountains. That\'s basically what you\'re looking at. How much
saturation is there of this carbonate material in the Funeral Mountains,
itself. So, you\'re looking at only one unit and we\'re looking at it
over a fairly limited area. And, we\'re saying to ourselves that the
discharge from that system are these major springs in Death Valley. So,
we\'ve got a very\--a much smaller picture, a much smaller piece of this
sort of regional model that Claudia was talking about.

BULLEN: Thank you.

NELSON: Ron?

LATANISION: Latanision, Board. I enjoyed very much your comments,
philosophical comments on modeling. And, certainly, my experience in
modeling bonding interactions in solids resonate with the comments you
made. But, I\'d like to turn to Slide 3 and ask you one question. It has
to do with the use of the word \"calibration\". In my experience\--and
I\'m just curious of your reaction to this, but in my experience in
bonding interactions, we often attempt to\--after developing a
conceptual model to use it to calculate something that is known; for
example, an elastic constant.

BREDEHOEFT: Right.

LATANISION: And then, to treat the model in order\--I hate to\--maybe
tweak or force, I\'m not sure which is the right language. But, to make
the model fit and then to use it to calculate something that is unknown
with hopefully some degree of confidence based on what I would describe
as not calibration, but verification or validation. Are we using the
same language?

BREDEHOEFT: I don\'t like those words, but that\'s okay.

LATANISION: Okay. Are we using the same language or is it just semantics
here?

BREDEHOEFT: Yes, I think we\'re using pretty much the same words.

LATANISION: Okay.

BREDEHOEFT: Let me back up. You have a conceptual model. You have some
observations. And, you adjust the parameters within your conceptual
model to fit the observations.

LATANISION: Right.

BREDEHOEFT: Okay.

LATANISION: Well, we use the model to calculate something that\'s known.
I\--

BREDEHOEFT: Okay. But, that\'s what we do, too. We say to ourselves,
okay, we\'ve got a bunch of water levels. Claudia talked about it.
We\'ve got a bunch of water levels out here. We\'re going to use the
model to calculate those water levels and see how well we do. We accept
the fact that we\'ve got to come back and adjust the parameters to make
a better fit to those calculated water levels. Okay?

LATANISION: Right.

BREDEHOEFT: But, what I\'m talking about here is in some of these cases
you come back and you say to yourself, hey, wait a minute, I\'ve got
data here which says that I can\'t fit this conceptual model. My
conceptual model doesn\'t work. So that, to me, is a very different
situation than where you say to yourself, we\'ve got observations,
we\'re going to change the parameter set to fit the observations, but we
didn\'t tinker with the conceptual model.

LATANISION: Yeah, yeah. Well, I wonder about the implications of this
short conversation on very complex engineering problems in which we
adopt, for example, the TSPA approach to dealing with all the many
variables that are involved. I mean, I\'m not quite sure how you could
do it otherwise. But, I do wonder about the fact that there is such an
overwhelming independence on modeling. How good is a calibration when
you\'re dealing with a very, very complex system as opposed to something
which I consider on the scale of things to be very simple and I\'m
talking about bonding interactions in solids? So, what\'s the
implication for TSPA based approaches to large engineering systems? Am I
putting you on the spot? I\'m sorry.

BREDEHOEFT: No, I\'ve been on this spot before. Let\'s look at the PA
for a moment. What you do in the PA is you say to yourself we\'re going
to accept the conceptual model over here. What we\'re going to look at
is suppose we made errors in our parameterization? So, we will run a
range of parameters through and look at what the model predicts with
this variation of parameters. But, we have not tested the conceptual
model. What was the conceptual model? I mean, I\'m saying the conceptual
model is wrong 25 percent of the time. You haven\'t tested that. And,
you haven\'t tested that with the calibration. You can calibrate to a
bad conceptual model. So, what you\'re saying to yourself is\--you know,
the implication of this is that you didn\'t test the conceptual model
and that conceptual model may easily have errors of some significant
amount associated with it.

LATANISION: Latanision, Board. The operative word from my perspective is
confidence. I mean, how much confidence can we attach to the
calculations that follow the evolution of a model and calibration and so
on? Once again, I don\'t know how to answer that, you know, on the scale
of things we\'re talking about, but it seems to me to be a very, very
important issue.

BREDEHOEFT: Let me try to answer it another way. It seems to be one of
the things you want to do is when you get through, you want to be sure
that what you\'re doing for society is robust and as robust as possible.
I think that\'s where you\'ve got to look to yourself. You know, you do
all the calculations. You say, okay, but then you say to yourself, well,
you know, is this system sufficiently robust to accept the fact that we
may have made some errors?

LATANISION: All right. Oh, I\'ll buy that. Thank you.

NELSON: Richard?

PARIZEK: Parizek, Board. John, you could have added to that answer what
you actually published and that is in terms of Yucca Mountain
application, one way to enhance your comfort level would be to perhaps
leave the repository open longer. Would you want to kind of add a little
bit to that?

BREDEHOEFT: You can do all these calculations and do all the PA and so
forth. I think there\'s still a reasonable chance that we\'ve made
errors. You know, that we didn\'t get everything right. So, one of the
things, it seems to me, is leave the thing open and watch it as long as
you can before you close it. I mean, you know, what\'s the rush to
closure? Particularly, when you get into a system like this where
you\'re presumably going to put hot waste in there and you\--I mean, I
don\'t know. You ask yourself how much confidence do you have in these
calculations when you now start getting things at 130 degrees, 140
degrees C. I don\'t have much confidence. But, that\'s just my bias.

PARIZEK: Thank you. That\'s a published statement so we can track that
one down. The other thing\--

BREDEHOEFT: I\'ve said 1,000 years, Dick. George Hornberger was arguing
with me that the 1,000 years is too long because we don\'t know what
society is going to look like in 1,000 years. But, assuming we had a
reasonable society, what is the rush to closure?

PARIZEK: One other question about the National Park Service, as an
example, as a constraint to try to understand something that could be
quite vital to the Park Service, as well as to kind of a national
understanding. So, here\'s a case where there may be times when perhaps
you have to violate pristine lands for the purposes of addressing
nationally critical issues. And so, again, you don\'t have to respond to
that, but it seems to me we really as an agent, at times, need to know
some answers to some critical things. And, if the spillway is really
kind of important to the backup of water in Claudia\'s model, then the
site-scale model and a lot of things cascade from it, I, for one, would
think that there\'s ways to gain access that would be not particularly
damaging perhaps. Again, other people have to weigh in on this, but I
feel strongly that there are times you\'ve been kept out of certain
terrain where maybe you ought to be allowed in that terrain in a very
controlled way in order to get this job done.

BREDEHOEFT: Dick, I would come back and say to you that the Park Service
has been most supportive. We have all kinds of very good cooperation
with the Park Service. And, you know, their concerns are that they
don\'t want some drilling rig sitting out there for two or three months
where the public is going to be\--you know, it\'s going to be obnoxious
for the public. But, they have been very supportive. So, I think we can
work those problems out.

PARIZEK: Thank you. That\'s a political answer, I think, but thank you.

BREDEHOEFT: One thing I would say, you know, one of the things at the
moment is the one hole we have at Yucca Mountain shows this upward
gradient from the carbonate aquifer into the overlying tertiary
material. Now, that\'s a protection for the carbonate aquifer. You know,
as long as that flow is upwards, you\'re going to have a hard time
getting waste to move into the carbonated aquifer. However, if you think
about sort of water supply and then we\'re going to go to that carbonate
aquifer as a big source of water, particularly for Pahrump where we have
water problems, they begin to lose that hydraulic head and you\'re going
to lose some protection from the aquifer as you reduce that hydraulic
head. And, the other implication of what we talked about is that those
springs are also going to be very sensitive to losing hydraulic head in
the Amargosa Desert. So, if we have development in the Amargosa Desert,
you can see where the springs are going to be impacted. You can see
where this upward gradient at Yucca Mountain would also be disturbed.
So, to the extent that Nevada develops that water, you can see very big
changes with respect particularly to carbonate aquifer.

NELSON: Nelson, Board. Let me ask you one question related maybe to
bring the two parts of your talk together that has to do with the idea
of designing experiments to test conceptual models so that specific sets
of observations get made that actually are addressing the conceptual
model uncertainty separate from the calibration issue of an existing
model. Do you think that that strategy has been used appropriately on
this project? Is it a strategy that should be used?

BREDEHOEFT: Oh, yeah, of course, it should be used. I mean, you know, if
you go back to the philosophy of science and you say to yourself all we
can do is invalidate which was Pauper\'s view of science, you know, then
you say to yourself, well\--set up these experiments to try to test that
conceptual model. You know, is it right or not? I\'m not sure I want to
say whether we did that well in this case or not. I\'m not sure.

NELSON: Nelson, Board. My experience has been that this is\--with the
reductionist framework that we\'ve moved into in many areas of science,
we tend to get a calibration or a testing of one model at a time with
one set of data so we don\'t have this possibility and it\'s a
shortcoming across the board.

But, let me ask you about maybe the vulnerability of this water system
if there\'s a climate change or a significant water table change in the
region. What are the potential impacts that this conceptual model would
predict?

BREDEHOEFT: You know, from the point of view of Inyo County and Death
Valley and so forth, you know, if you get more water in the system,
that\'s helpful. We\'re going to get bigger spring flows, probably
increase the head in the carbonate aquifer, those kinds of things. That
would be helpful. And, I think, most of the climate change\--I sat there
yesterday, I don\'t know. It seems to me that we\'re in a more dry
period of the climate at the moment. So, probably what you\'re looking
at is winter conditions. And, as far as the carbonate aquifer, that\'s
probably beneficial.

NELSON: Nelson, Board. Does your model indicate any vulnerability for
loss of that upward gradient to flow that protects that resource?

BREDEHOEFT: Well, it seems to me if you come to the northeast side of
the Funeral Mountains and you say the hydraulic head at that point is
controlling the flow through the Funeral Mountains, if you reduce that
hydraulic head with development, that\'s going to be detrimental as far
as the springs are concerned.

NELSON: Okay. Any other questions?

(No response.)

NELSON: Staff?

(No response.)

NELSON: No. Well, we thank you very much.

BREDEHOEFT: Uh-huh.

NELSON: We are three minutes ahead of schedule. You do get that three
minutes on your break. So, we will reassemble here to the tune of some
music at 10:10.

(Whereupon, a brief recess was taken.)

NELSON: Regardless of whether Richard Parizek is back, we\'re going to
start. So, grab your coffee and have a seat.

I want to just make one clarifying statement and where I was coming from
in my question regarding conceptual model testing and I think it
permeates many, many fields of science and engineering.

There\'s a major project at the National Science Foundation right now
called the Network for Earthquake Engineering Simulation. And, in the
field of earthquake engineering, perhaps reinforced by National Science
Foundation\'s grant policy, has been a long string of small awards given
to single investigators to investigate their model in their context and
gather their data through their experimental setup. With the Network for
Earthquake Engineering Simulation, what\'s going to be set up is a
complete collaborative environment where data, visualization, tools, and
analytical codes are all available to the entire community where each
project that comes forward will be placed on the Web and anybody in the
community can propose parts to the experiment, piggyback opportunities
on the experiment, that will actually allow many models to be tested
with one experiment. It\'s going to be a culture change and it\'s
probably going to be somewhat painful, but I think that it\'s where the
future of many aspects of engineering is. So, that\'s where I was coming
from in that specific example.

But, it\'s my pleasure to reconvene this session and to get a little bit
more up close and personal towards the site. And, it\'s my pleasure to
introduce Jim Winterle. Jim received his bachelors and masters degrees
in hydrology from the University of Arizona at Tucson and he comes to us
as Senior Research Scientist with the Geohydrology Group at the Center
for Nuclear Waste Regulatory Analyses in San Antonio, Texas. For the
past six years, he has been a principal investigator on saturated and
unsaturated flow issues related to the proposed high-level waste
repository at Yucca Mountain under contract to the U.S. Nuclear
Regulatory Commission. His work at the Center allows him to apply his
broad variety of hydrology interests which include interpretation of
aquifer pumping tests, aquifer responses to earth-tide and barometric
effects, contaminant transport in porous and fractured media,
groundwater flow monitoring, multi-phase mass and energy transport
modeling, recharge estimation, and the interpretation of groundwater
temperature patterns which are of particular interest to me.

So, I invite Jim to the podium to make his presentation. Thanks.

WINTERLE: Thank you. Thanks to the Board for inviting me and to the
Staff and technical people for putting on such a great set of
presentations.

I\'m really glad to follow John Bredehoeft\'s presentation not only
because he\'s such a distinguished scientist, but because his
philosophical comments on conceptual model testing lead nicely into what
I\'m about to present.

I thought before I start that, I\'d offer a few philosophical comments
that I\'m borrowing from a recent article in the latest issue of the
Ground Water Journal by Amat Hussan of Desert Research Institute. He
argues that the term \"model validation\", which inspires a lot of ire
in some hydrologists, is acceptable, but as long as it\'s understood
that we\'re referring to confidence building. And, some of the
statements borrowed from him is that model validation is a process, not
an end result. That is that the process of model validation cannot
insure acceptable prediction or quality of the model. Rather, it
provides an important safeguard against faulty models or inadequately
developed and tested models. If the model results become the basis for
decision making, then the validation process provides evidence that the
model is valid for the decisions, not necessarily a true representation
of reality.

And, I think we see that a lot in the Yucca Mountain Project. It\'s when
we have a set of competing conceptual models, we often pick the more
conservative one if there\'s no data to support any one over the other.
In cases like that, we\'re pretty sure we\'re not reflecting reality,
but we\'re pretty sure we\'re building a sound basis for decision
making.

The purpose of this model that I developed of the Yucca Mountain site is
to test conceptual models and I\'ll start off with the usual notes that
this work was funded by the Nuclear Regulatory Commission, but nothing I
present here necessarily represents their regulatory position. And, that
the model scenarios and results I\'m about to present are exploratory in
nature and intended to gain a better understanding of what affects the
flow system and nothing should be considered as a preferred model.

I\'ll get into the outline. I\'m going to talk about how the model is
based on the hydrogeologic framework, the effects of hydrogeologic
interpretation on the model calibration and how that affects groundwater
flow paths. Then, I\'ll go into a second set of analyses on effects of
local recharge in the repository area and how that drives flow paths
into different portions of the aquifer. And then, a third set of
analyses that I\'ve heard inklings of interest in is the effects of
increased recharge and water table rise possibly due to a future climate
on the model flow paths and travel times of groundwater.

The hydrogeologic framework model that we start off with is developed
independently at the Center. So, we\'re starting off with a completely
independent interpretation of the geology as the basis for this model,
although one of the data sets did go into this interpretation was the
USGS GFM Model 3.1 which was also an input to the DOE\'s model. It\'s
one of our inputs and we interpreted that model somewhat differently by
lumping hydrostratigraphic layers with similar properties that are
adjacent to each other into single units. So, that interpretation is
also different from the DOE approach. Then, we extended the model region
based on the Center\'s interpretations of geology and geophysics. And
then, I took that as the basis, extracted a region from that model and
assigned hydrologic properties based on the correspondence to units.

There\'s also several faults and structural features in the model. You
can see pretty much everything on this graph is in the model, all these
different faults. There\'s a caldera zone in the hydrogeologic framework
model. This red line shows where I had to actually extend that region of
the caldera southward in order to obtain a better calibration. That
would correspond to something in the DOE model that they also had to do
that they called a northern region or northern zone. I forget the exact
name of it. And then, the other modification is I had to extend the
Highway 95 fault zone just a little bit from where it was in the
original model and then pretty much everything else is similar.

I think I missed a couple points here. Yeah, some of the other changes
were the Bow Ridge, Midway Valley Fault zone, Paintbrush Canyon Fault
zones here in the middle of the mountain. These faults are all so close
together that I just discretized that into a single fault zone and then
I made a separate fault zone for the entire area between the Paintbrush
and Fortymile Wash Fault as part of the model construction. Then, that
was all discretized into a 300 meter horizontal grid size. Vertically,
the smallest grid sizes near the water table is a 15 meter vertical grid
discretization. That\'s that.

And, this shows you a comparison of the underlying hydrogeologic
framework model and then how that ends up in the flow model. This is a
cross-section through the middle of the model domain that goes through
about the repository area, east-west. And, you can see the different
material colors that I used to incorporate faults. I didn\'t extend the
faults all the way down to the bottom of the model domain. I just keyed
them into the underlying permeable unit. This brown unit here is a
low-permeability volcanic confining unit that extends over a good
portion of the domain. The paleozoic carbonate units, the lowermost
unit. The lower volcanic aquifer. This blue layer is an upper, what we
call, a confining unit, but it\'s actually semi-confining. It\'s a
little bit permeable compared to this brown volcanic confining unit.
Then, the upper volcanic aquifer in gray and then the alluvium is in the
lavender color.

The model domain, you can see in the square box over the satellite map
and then I used the interpretation of water table based on water levels
and heads to get a starting point for the top model boundary. The top
boundary is something I used in MODFLOW. It\'s called a
confined/unconfined flow boundary. It allows\--if there\'s not enough
flow into a cell to keep that cell saturated, it allows it to go dry and
become inactive. And then, if you should increase recharge during a run,
theoretically, it lets it re-wet and become active again during a
simulation. So, I set the top seven model layers in that mode because
those were within the range where the water table might become active or
inactive in a cell. No-flow bottom boundary. The size of the domain is
28.5 by 41.4 kilometers. It extends from 1500 feet below sea level to
1200 feet above sea level. And, 70 wells used for calibration points.
Recharge points were in the north area and also considered in the Yucca
Mountain area and Fortymile Wash area for certain scenarios.

There\'s an oblique view of the model that you can see how the top of
the model tapers down in active cells where the water table drops down
to the south. You can also see certain faults in the model and the
different configurations of the material types.

The first analysis I\'m going to present is how we\--so the question we
asked is\--the DOE has got their model and it\'s got a certain amount of
calibration error. Somewhere about the means^2^ error in their model for
80 or so wells is about 30 meters which, you know, 30 meters a head off
in a well could be a lot. So, our question was is that something that\'s
drastically going to affect flow paths where travel time is commenced?
So, we set out to take a standard model and calibrate it as best we
could and then to take an alternative model and shift things around a
little bit to get the calibration even better.

In this model, we didn\'t necessarily constrain ourselves to having
features supported by data. For example, you know, along these fault
zones, you have big head drops in some areas and that seems to be where
you get a lot of your errors in the model. So, one of the ways to fix
that is to take a model cell and shift it over to the right one or make
your fault zone two model cells wide instead of just one model cell wide
and you can reduce a lot of error that way. Another thing we did was to
sculpt the shape of this caldera zone. Another adjustment we made was in
some areas between the alluvium and tuff interface, we put transitions
on that had a lower permeability. And, there\'s conceptual bases for all
of these, but they\'re not necessary supported by data and that\'s why
we\'re calling this an alternative scenario. The contours on here show
the different calculated water table elevations and they\'re not that
different between the models to look at.

But, when you look at the calibration, the original model had an RMS
error of 27 meters, very similar to what the DOE. That was the best we
could get using a trial and error approach. The biggest errors were up
in the north area where heads are high. So, they\'re not necessarily
problematic because they\'re off at the flow paths. Then, the second
zone of high errors is what we found mostly along fault zones where
there\'s a steep change in the water table gradient. So, that\'s where
adjusting the fault zones left or right came in handy. And, if you look
on the right, we were able to get our RMS error down to 1.1 meters on
average with 70 wells just by moving things around a little bit. And,
that was all trial and error and adjustments. It took one person full
time about a month to do this which if you had to set a PESS simulation
up, there\'s just so many parameters, it probably would have taken it a
month to run anyway. So, we were happy with it. The error is down in the
range of what the water table measurement error is. So, we decided
that\'s a good stopping point. We\'re really not going to get any better
than that.

So, let\'s compare the results of the two models. On the left, you see
the original model has flow paths going pretty much to the south. What
happens is they start flowing east and then they hit a zone where Bow
Ridge, Paintbrush Canyon Fault zone, it\'s more permeable than where
they started out and that\'s like a stream going into a river and it
just makes the turn when it hits the river and then it just flows
straight south.

In the alternative model, the distribution of permeability is going east
to west. It didn\'t really change drastically until we hit the Fortymile
Wash Fault zone. So, they go a little bit farther to the east before
they also make a quick southward turn and essentially end up in the same
spot. I should say about this alternative model, along the way we did
several analyses of flow paths when we were adjusting different features
and there\'s a lot of calibrations that are nearly as good or almost as
good that didn\'t go as far east as this and pretty much looked the same
as the original model. So, you could view this alternative as the
farthest east we could get those flow paths to flow and it really
happens to be a very good calibration at the same time.

And, comparing that to the latest DOE model predictions that we have
access to, you can see they\'re generally in the range of between what
these two models are predicting and also end up in essentially the same
point at the end. So, you know, starting with a completely different
model, completely different approaches, and completely different levels
of matching your calibration data, there\'s not a big variety in flow
paths. So, that\'s the end of this interpretation before I move on to
the next one.

I\'m not going to show you the travel times for these two flow paths
because there were some things I didn\'t like about that that will come
up in the next analysis. But, just to say that the travel times didn\'t
differ too much between these scenarios. So, that gives us confidence
that we don\'t really need to go in and collect enough data so that we
can get our calibration down to one meter and still accept the results
for the purpose of the model.

So, the next thing I wanted to look at was the effects of recharge in
the local Yucca Mountain area because when these flow paths from the
unsaturated zone hit the saturated zone, the amount of recharge affects
the downward gradient and it\'s going to drive them into the system and
hence the flow paths. So, we wanted to know how important it is to get
that recharge rate on the saturated zone flow paths. So, Case 1 only has
recharge in the area to the north which they assume to be 10 mm/yr for
this analysis and nowhere else. Case 2, I added the yellows on of 5
mm/yr which is pretty close to the average infiltration rate base case
that the DOE is using. For a later simulation, I\'ll talk about
recharging Fortymile Wash, but that\'s not in the ones I\'m about to
show you.

For the case with no recharge in Yucca Mountain, the flow paths are
pretty much the original case I showed you from the last analysis. And
then, with 5 mm/yr recharge in Yucca Mountain, they don\'t look very
different, at all, until you look at it in the vertical view. And, you
can see that with no recharge, they stay very shallow near the top of
the aquifer. And, with a little bit of recharge, they go down quite a
bit deeper down to about\--most of them are no deeper than about 300
meters, although there\'s a couple of stragglers that go deeper. That
lengthens the flow path some and then also spreads out where they arrive
at the 18 kilometer point.

In terms of travel time, there\'s a big difference. I think I should
show you that for the original case, it\'s sort of a bimodal
distribution. The earliest times came from the south end of the
repository and then the longest times stretch out beyond 10,000 years
for quite a few of the flow paths for almost the whole northern half of
the repository; whereas the case with only 5 mm/yr recharge in Yucca
Mountain significantly shortens that. So, even though the travel
distance is a little longer for these deeper flow paths with the
recharge, the mean travel time in this scenario\--remember, we\'re not
talking about reality here; this is a model\--is 1,000 years going up to
a couple thousand at the most; whereas this has travel times going up
into the 40,000 year range.

So, what\'s the deal with groundwater travel time between these two
simulations? Why are they so different? That gets into what I had to
make assumptions about for the porosity. In my simulations, I assigned a
value of .001 for welded tuff units, and then for nonwelded tuff units,
such as that upper volcanic unit which corresponds to the Calico Hills,
I gave it a value of .1. My basis for that was that there\'s quite a bit
of well data that shows that\'s a relatively unfractured porous type of
formation and so we might expect a different flow regime in that unit
than in the tuff units. So, as most of the hydrologists know, for a
given flux, the average groundwater velocity is going to be inversely
proportional to that porosity.

In the simulations where I had no recharge at Yucca Mountain, the
shallow flow paths traveled a much greater distance through this upper
volcanic confining unit and that is the main reason why you had a
distribution of flow paths that went beyond 10,000 years to the range to
several thousand. And, it\'s solely because I\'m assuming a value of .1
for that upper volcanic unit. If I did as the DOE assumes in their
performance assessment and set all volcanic units to the same value of
.001, in that case it makes very little difference whether I have
recharge or not in the Yucca Mountain area to the flow paths. So, take
away from this is that although nobody is currently doing it in
performance assessments, there\'s a possibility that this UVC, upper
volcanic confining unit, the Calico Hills unit, could have a porous flow
regime that would add a lot of time to the groundwater flow path. And, I
already mentioned that historically most of the performance assessments
have been conservative in their assumptions about that.

The next analysis I\'m getting into is the potential effects of climate
change and I guess I should say a little bit about my thinking process
that went into what\'s going to happen to the water table when climate
changes. You know, this all went on inside my head, and one afternoon in
my office, I decided that here might be a good way to approach it, and
by the end of the afternoon, I had model results that I\'m presenting to
you today.

So, what I thought about was would it be a uniform water table rise? In
that case, there was really no point in running the model because it\'s
not going to change the gradient if everything rises the same amount.
The hydraulic gradients are all going to be the same. And then, I
considered that, well, what\'s really probably going to happen is
you\'re going to get more recharge in some areas and that\'s going to be
the area where the water table rises the most is in the areas of higher
recharge. So, in the original model, the highest recharge areas had the
highest starting heads on the boundary. So, I decided rather than raise
the heads by a fixed amount, to raise them by a fixed proportion. So,
that way, the groundwater table rise was higher in areas where there was
higher recharge and higher boundary heads.

So, I arbitrarily picked 5 percent as my first amount and that happened
to work. What I used as a constraint was this location of approximately
around Nye County Well 9S. In that location, there were some evaporate
deposits where historically you can infer that water table has
intersected the groundwater surface in that area and that I should
constrain the model by rising the water table enough so I just initiate
some groundwater flow in that area. I used MODFLOW as a drain package
where you put a cell in there. And so, I raised it by 5 percent and it
just happened at the elevation of those evaporate deposits, it was the
first portion in the entire model domain where the groundwater table
intersected the surface. And, at that amount of increase, there was just
a trickle coming out of that drain cell, about a meter cubed per year,
which is consistent with the formation of the evaporate deposits, a slow
seep coming out that can evaporate and leave deposits behind. So, that
was my constraint and I got lucky and nailed it on the first try of
water coming out of there.

The other thing I changed was I doubled the recharge in the north
region, doubled the recharge in the Yucca Mountain region, and added 200
mm/hr recharge in the Fortymile Wash region. That is arbitrary and if
anybody would like to suggest to me different values of recharge
increase, I\'d be happy to test them. But, in the meantime, I\'ll show
you the results for this particular scenario.

And, that is that I got a water table rise constraint here at 9S that
was equal to the ground surface of about 30 meters and that increased to
the north. In the repository area, the water table rise was between
about\--I didn\'t write it on here\--I think, it was between about 70
and 150 meters\--70 to 120 meters was the water table rise. And, that
just happens to be very close to what the Department of Energy models
are assuming for water table rise in their model. And, you can see it
increases from north to south which might\--if any future modifications
should take that repository horizon farther north, you can see the water
table rise could be in this model scenario much higher than that 50 to
100 meters. So, that might be a factor to consider if there were any
changes in that footprint area.

The other thing we considered was how does that change flow paths? The
Department of Energy, the last model version that I had access to,
treated climate change by just increasing the fluxes through the model
by, I think\--Bill Arnold can correct me\--I think, a factor of 3.9. And
so, what we wanted to know was how much do the fluxes change in an
alternative scenario where we actually raise the water table elevations.
And, you can see that the flow paths don\'t change much, at all, for the
before and after scenario. If you study it closely, there are some minor
differences, but nothing that we would consider significant.

The case with travel times is also not that much. There\'s a few
particles get there a little bit earlier with the higher water table.
Again, in this scenario, I\'m considering the porosity distribution that
I presented before. There\'s that thin tuff layer with higher porosities
than the rest of the tuff. And, you get one flow path that\'s a little
bit longer than the longest flow path for the present day case, but on
average, they\'re not that different in terms of travel time.

So, those are the three analyses I wanted to present today. And, the
conclusions that I come away with are that the model calibrations can be
significantly improved by relatively minor adjustments to interpreted
geometries and hydrostratigraphic layers and structural features, but
the variability of the flow paths and travel times for the two scenarios
was only modest.

Considerations of small amounts of recharge to the potential repository
has a significant effect on the depth of the flow paths and volcanic
units through which they travel. However, the further increases in
recharge above that 5 mm/yr did not appear to add to that effect. What
I\'m saying is in that climate scenario when I had further doubling of
the recharge in the repository area, those travel times didn\'t change
much from the present day or the flow paths.

The comment I made on the porosity of the upper volcanic confining unit
can have a dramatic effect on the groundwater travel times to the
compliance boundary. If data collection efforts or perhaps mining of
existing data were to focus on evaluating that porosity, it might
improve the understanding of the effectiveness of the saturated zone
barrier.

An assumed 5 percent increase in the boundary head values to account for
a potential water table rise results in initiation of model groundwater
rain flow near the Nye County Well 9S which is consistent with the
location of the spring deposits. That 5 percent boundary head scenario
resulted in a water table rise beneath the repository of\--oh, here\'s
where I had it\--50 to 150 meters, increasing from north to south, and
those potential effects should be considered if repository footprint is
extended to the north.

The scenario of combined water table rise and increased recharge
including additional recharge at Fortymile Wash did not significantly
change model groundwater flow paths or travel times to the compliance
boundary.

And, that\'s the end.

NELSON: Thank you, Jim.

Could we look at Slide 14 just for a minute? I guess, I was really
struck by the apparent importance or impact of having recharge right on
the Yucca Mountain area on the flow paths. But, I\'m not sure I
understand the difference between these two figures in terms of what the
subsurface stratigraphy is showing because they are a bit different.

WINTERLE: Okay. Without the recharge, you see this blue layer here?
That\'s that high porosity unit. And, there\'s nothing to really drive
them down through that unit. So, they tend to stay up there and travel
very slowing, especially the ones initiated in the north end of the
repository. That\'s why I had that bimodal distribution on the travel
times where some of them were getting there quickly, but you know, the
north end of the repository was taking an excess of 10,000 years travel
times. And, it was all due to this significant difference here. And, in
the lower scenario\--these are actually the same model, though you see
different stratigraphy. I made a mistake and took a slice from the next
cell over in this model. But, you can see that that recharge drives it
down through that zone and then at that point it\'s into the permeable
unit with low porosity where for a given flux it just flies along at a
higher velocity.

NELSON: Okay. Nelson, Board. What\'s the total thickness of these
sections?

WINTERLE: In the upper zone here where I\'m pointing, the top 10 layers
or so, each of those grid cells is 50 meters. There\'s a 7 to 1 vertical
exaggeration here. So, it looks exaggerated as to how far those are
coming down, but it adds maybe 200 meters to the flow path which isn\'t
much in terms of an 18 kilometer transport distance.

NELSON: Okay. Bullen?

BULLEN: Bullen, Board. Could we go to Slide 13, the previous slide? I
just had a quick question for you because one of your conclusions stated
that if the repository is shifted a little farther north that you may be
getting close to the water table rise. That would be a problem if, for
example, you did the 5 percent increase in recharge rate. But, what
repository footprint did you use for the calculation? Was it the SR
footprint or is it the more recent\--

WINTERLE: It was, I believe, from the SSPA which looked slightly farther
north.

BULLEN: Bullen, Board. Actually, the most recent footprint we see has
the north ramp and, you know, four different panels and the like. Have
you seen that latest layout and does that actually overlap with some of
the areas that have like the 250 meter rise?

WINTERLE: That\'s a good question. I can\'t answer it. I have seen
drawings of that. They haven\'t filtered down to our database to the
point where they can be incorporated in the models. But, I would say if
they\'re getting up into that north area around where Well G-2 is or
even just a little bit south of that, then it might be something to
think about how close that water table could get.

BULLEN: Bullen, thank you.

NELSON: Parizek?

PARIZEK: Parizek, Board. Thank you for your presentation. It was very
interesting. On Page 21, it\'s sort of surprising that when you turn on
the pluvial again, you end up with a rise about 30 meters at the paleo
spring deposit and from 50 to 150 meters under the footprint. That gives
you a steep gradient and yet that didn\'t seem to change the travel
time. You\'ve got a much steeper gradient. So, you\'d think that you
ought to get a greater velocity out of this. Can you explain why that\--

WINTERLE: The real steep gradients are mostly just north of the
repository area and in low-permeability units. And, also, they\'re steep
because the recharge was increased in that area and it\'s a
low-permeability zone. So, there actually may be some conceptual
problems with my interpretation there where the zone where I\'m showing
several hundred, like 300 meters, of rise in the far north portion, the
rock there might not be able to accept that much water. So, it might
actually be more runoff and less of a water table rise in that area.

PARIZEK: Parizek, Board. With regard to the precipitation amount to get
the springs, I guess at the Horsetooth formation, the paleo spring to
just begin to seep, there are several other paleo spring deposits in
that area. How much more precipitation would you need to maybe kick
those in or would that be another trivial amount or not? I mean, it\'s
good that you got them to come out, first of all.

WINTERLE: Yeah, it\'s actually the whole zone around there. The 9S area
was the first one, but there was just north of there on the other side
of those hills, that little corner of Crater Flat that tucks down behind
the Highway 95 area, there was\--very close to the ground surface,
hydraulic heads there. And, I believe, down in the southeast corner of
the model, they were getting pretty close to the ground surface which
is\--Ash Meadows isn\'t in the model domain, but you\'re getting down
towards that area at that point in the model.

PARIZEK: Parizek, Board. They\'re going in the right direction. So,
that\'s encouraging.

Figure 14, you had some black dots in the upper diagram. I don\'t know
what those are.

WINTERLE: Those were the calibration points.

PARIZEK: Okay, I\'m sorry.

WINTERLE: Yeah, a point I should have made was that the calibration
points cover a variety of depths, not just horizontal distributions. So,
we\'re matching upward gradients in our calibrations, as well.

PARIZEK: Does the model require anisotropic properties in the role of
faults built into here in order to get\--

WINTERLE: I assume\--

PARIZEK: I mean, your calibration is so fantastically exciting, you say,
maybe I shouldn\'t believe it. But, I mean, what did you do with your
faults and anisotropy?

WINTERLE: Every model cell was assumed homogenous and isotropic here and
it\'s just I played around with the position of them and it\'s sort of
like sculpting a statue. It\'s like, well, that doesn\'t quite look like
I want it to. Let\'s move that cell this way or that way. You know, to
me, that\'s a little more defendable than getting an inverse code like
PESS and say, well, you decide where the permeabilities need to be
highest. At least, you know, I\'m in control of the conceptual basis for
where I move a cell. And, I\'m sure a PESS simulation could have given
me a heterogeneity plot that looked like a shotgun blast and maybe come
up with as good a calibration, but I wouldn\'t be able to defend where
to assign the permeabilities.

PARIZEK: Parizek. One other question. That\'s on the Fortymile Wash. You
had a green line that you were going to put into another run. Which run
actually had the Wash recharged?

WINTERLE: That was the water table rise scenario. I doubled all the
recharges in the north and Yucca Mountain area and added 200 to
Fortymile Wash.

PARIZEK: Yeah, and again you were asking for challenges to what\'s
better than 200 or\--

WINTERLE: Yeah, that is arbitrary.

PARIZEK: You\'re not sure where the chemistry or isotropic data might
help put some limits on that?

WINTERLE: Yeah, I thought to maybe include a river package in MODFLOW
for that. I don\'t know if the Fortymile Wash would be a perennial
stream in a future climate. There\'s different ways to look at it, but I
thought 200 mm/yr is a pretty good slug of water compared to what\'s
going through there now. And, if that\'s not going to move it\--

PARIZEK: And, unlike Claudia, you didn\'t have any lakes on top of any
mountains, did you, in your runs?

WINTERLE: No.

PARIZEK: Okay, thank you.

NELSON: Thure and then Ron and then one from Staff.

CERLING: Cerling, Board. I guess this gets into the issue of calibration
versus validation. So, in one of your models, your wetter model, you
increased in the distal regions groundwater by 30 or so meters to have
it come out the same as a paleo spring deposit, and then further up, you
proportionally increased the groundwater table.

WINTERLE: Right.

CERLING: And so, what I\'m wondering is there any evidence that you can
use to corroborate that higher level in drill cores that has to do with
petrographic evidence, stable isotope evidence, etcetera? Have you
looked for that to see?

WINTERLE: That would be good to have some data. It would be nice to have
some access to walk around in those hills up there and look for old
spring deposits perhaps as a constraint on how high water table has
gotten in the north. You know, based on what I have, all I could do was
make some arbitrary assumptions.

NELSON: Ron?

LATANISION: Latanision, Board. Of the long list of KTIs that are of
interest in discussion between the project and the NRC, are any of those
encompassed by the work you are doing, and if so, can you give us some
indication of what the state-of-the-art is?

WINTERLE: Oh, the KTI, this work was all done on the
unsaturated/saturated flow under isothermal conditions, KTI. The status
is we\'ve\--what we\'re focusing on now is the agreements that were made
back in the 2000-2001 technical exchanges where based on our review of
the site recommendation and our preliminary review of the SSPA document,
we had given DOE an indication of what we had thought were the extra
things they needed to provide to defend their model and to move toward
LA. Since then, a lot of models have changed and, you know, we\'ve got a
whole round of these technical basis documents to review now. I think,
in a lot of cases, you know, the changes have been more defensible. In
some cases, the changes, as far as we can tell, so far, are not
defensible. I don\'t know what\'s going to happen when an LA comes in,
if there\'s going to be another round of technical exchanges. You know,
I can\'t speak for the NRC. I would imagine there\'s going to be some. I
find it impossible to think that there won\'t be any comments on an LA
that haven\'t already been raised, but where we\'re at now is we\'re
probably\--part KTI is about halfway through resolving the agreements
that we have made. There\'s maybe 15 or 20 left, I think.

LATANISION: Thank you.

NELSON: Dave Diodato?

DIODATO: Diodato, Staff. Thanks for a very nice presentation, Jim. I
wanted to look at Slide 15 first just for clarification. The Case 2 on
the bottom, that would be for a conserved species, right, with no\--

WINTERLE: Yeah, that\'s a Mod Path particle tracking simulation which is
designed to go where the groundwater goes. So, think of it as a water
molecule.

DIODATO: All right, thanks. So then, there are none of the phenomena
of\--

WINTERLE: Yes, no matrix diffusion, no dispersion. The only dispersive
effect would be the macro dispersion of the various flow paths coming
through.

DIODATO: Thanks. So then, if we back up to Slide 14 and look at the path
links, you talked about the importance of porosity in the volcanics in
terms of determining the velocity of that water molecule. And then,
also, the path that it follows, you have this in cross-sectional view
and you had the other simulation aerial view. Could it make a difference
then in terms of how much matrix diffusion would occur during sorption
depending on if you\'re in the volcanics or if you\'re in the alluvium
and that sort of thing, adding those things in? Do you think that then
that might potentially be something that would make you look at your
conclusion that it doesn\'t make a lot of difference in travel time? I
mean, if you add that other layer of complexity into it, could it
potentially then make a difference, the path of groundwater flow?

WINTERLE: I\'m not sure I understand the question. Could\--

DIODATO: The question is like\--yeah, I worded it poorly. So, let me
rephrase it. So, if the path of groundwater flow\--your conclusion
initially was that travel times aren\'t all that much different. You
know, they\'re all about 1,000 years for the water molecules, the
particle tracking simulations. But then, if you consider the effects of
matrix diffusion and sorption, would that potentially cause you to alter
your conclusions about one model versus another model?

WINTERLE: Yeah, I would think that if I had to pick a model to believe
in, I\'d take the one where they\'re going a little bit deeper because
we can be pretty sure there is some recharge. So, even with those deeper
flow paths, they do go through a portion of this upper volcanic unit and
I would think that, you know, the porous flow regime would make for a
lot more sorption capacity than just matrix diffusion occurring in the
fracture flow parts of the domain. So, I would say not so much the case
of whether or not there\'s recharge would make a difference in that, but
the case of whether or not you consider porous flow in that particular
layer could make a big difference and even a bigger difference when you
take into account radionuclide transport.

DIODATO: Thank you.

NELSON: One question reserved for me. Can you tell me what your studies
tell you about what the permeability of the faults must be?

WINTERLE: What the permeability of the faults must be?

NELSON: Is it high? Are they high-permeability, low-permeability\--

WINTERLE: No, well, just to get a calibrated model, pretty much\--I
can\'t see how you can get around it. You have to assume that the
Solitario Canyon Fault is low-permeability. I haven\'t looked at
anisotropy if it\'s directional permeability matter. But, you also have
to assume that in the Bow Ridge, Heepress Canyon (phonetic), and
Fortymile Wash regions that those faults are high-permeability. And, you
also have to assume that whatever that structure is in the Highway 95
zone, whether it\'s a fault or just some altered rock region, you have
to assume that\'s low-permeability.

NELSON: Nelson, Board. So, most of the flow is actually running
along\--much of the flow is captured by the fault zone?

WINTERLE: It\'s not really captured in that in the case of Highway 95
and\--

NELSON: Oh, I\'m sorry, I was thinking about east of the Yucca Mountain.

WINTERLE: Oh, east? Yeah, because it\'s higher permeability, the
gradient runs toward it. Once it hits there, it turns abruptly south.
Now, the difference between reality and my model is that that transition
is probably not quite so abrupt as, you know, one minute it\'s in
low-permeability and the next second it\'s in high-permeability. So,
those turns to the south could be a little more gradual is maybe one
difference.

NELSON: And, the exit point from the fault zone or from the rock into
the alluvium is similar for your model than to DOE\'s model?

WINTERLE: It\'s similar. The DOE model is\--we don\'t really have a lot
of cross-sections out of their hydrogeologic framework model to
understand so much the geometry that\'s incorporated into their model.
That\'s one of the agreements we have is that we\'re trying to get
cross-sections of the alluvial basin and comparisons to their model. We
don\'t have that information yet. That\'s a key uncertainty we want to
explore also is the nature of the tuff-alluvium transition and that\'s
probably something we\'ll use this model for in the future is to look at
different versions of that.

NELSON: Okay. Closeout question to Richard?

PARIZEK: Parizek, Board. On Page 7, you show some contours that are kind
of wiggly up near the footprint and I\'m just wondering what the basis
for that contouring is? The diagram shows a pretty smooth contouring
interpretation in that same general area.

WINTERLE: The interpretation is that\'s\--you\'ve got to wiggle them
like that to match the\--if you assume that those hydraulic head ops or
water table elevations are within 10 centimeters of the true values, you
have to wiggle them like that. Potential explanations for that could be
that there\'s a couple of areas where some flow leaks through the
Solitario Canyon Fault causing those two bulges that come out through
the side there.

NELSON: This really is the last one.

PARIZEK: I might alert Ken Rehfeldt later on that when we get to his
Page 19, we compare the two and see whether

he\--his is smooth, yours is not. So, we just want to understand the
basis. Thank you.

NELSON: Thank you very much, Jim. It\'s very hard to corral the senator
from Pennsylvania sometimes.

Okay. We move into our final talk of this morning and I\'ve been asked
by Russ Dyer to have an opportunity to make a preemptive statement
before we ask Ken Rehfeldt to come up.

DYER: Thank you. Before we move into the next four presentations, I\'ve
been asked to repeat a disclaimer associated with a topic on here, the
expected or median travel time of a water molecule. The talk I\'m going
to give is exactly the same talk that I gave yesterday except for the
last slide. I just want to highlight a couple of things.

Again, I want to repeat that the presentations that you\'re going to
hear do not address the expected travel time of a water molecule either
in the unsaturated zone or this afternoon, you\--or subsequently you\'ll
hear about the saturated zone.

Secondly, we don\'t routinely do such a calculation. We have done such a
calculation in the past which I\'ll show you on the next slide, the same
slide that was shown yesterday. We don\'t think that any of the
information that\'s been garnered in the resulting several years would
change the results much. We showed this yesterday and talked about it a
bit. What you\'ll be talking about today primarily would be the
saturated zone part of this.

The final thing I\'d like to point out is that for the four remaining
presenters\--that\'s Ken Rehfeldt of Los Alamos, Gary Patterson of the
U.S. Geological Survey, Stephanie Kuzio and Bill Arnold of Sandia
National Labs\--in the information that they present, they\'ll be using
radionuclide breakthrough curves to list a predicted transport behavior
of\--just a minute\--of calibrated saturated zone models and
abstractions. Those breakthrough curves don\'t represent the expected
travel time of water molecules. They portray a full probabilistic
sampling of input parameters. And, as you probably picked up from
George\'s presentation yesterday, they\'re often developed with very
conservative inputs to fully assess the impacts of uncertainty.

Thank you very much.

NELSON: All right. We\'ll move on and invite Ken Rehfeldt to come up to
the podium. Dr. Rehfeldt received his PhD from MIT, that place where
some people know about, in civil engineering. So that he\'s one of the
good guys; no bias there. Ken works on saturated zone groundwater flow
and transport studies for the Yucca Mountain Project. He has more than
20 years experience in the field of groundwater hydrology including more
than 10 years in the assessment and modeling of groundwater flow and
radionuclide transport from the underground nuclear tests at the Nevada
Test Site.

And, we are very interested in hearing you.

REHFELDT: All right. Thank you very much. It\'s a pleasure to be here.

What I want to talk about just before lunch here so we can let you go
and have some lunch is to briefly talk about the conceptual model of the
saturated zone flow and transport at the site-scale, but primarily to
concentrate on some of the independent lines of evidence that we use to
give us more confidence in those model calculations.

I want to point out that this was a collaborative work with a great many
of the researchers both at Sandia and at Los Alamos. In fact, this is
their work. The modeling that I\'m going to present is not the work that
I\'ve done myself, but it is the work of these folks here.

So, the outline of the presentation is I\'m going to very briefly talk
about the conceptual models of groundwater flow and radionuclide
transport and you\'ll hear more about that a little bit later this
afternoon from both Bill Arnold and Stephanie Kuzio. And, I\'ll show you
some of the site-scale flow and transport model calculations, some of
which you\'ve already seen this morning and then work primarily to
present the independent lines of evidence to support those calculations.

Here is the outline of the site-scale model that\'s sitting out here.
And, as Claudia pointed out earlier this morning, the site-scale models
sits inside of a much larger flow system, the Death Valley regional flow
system. And so, what goes on in the site-scale is not independent of the
regional. In fact, the Death Valley flow system provides a fair amount
of control over the site-scale model. It defines general flow
directions, recharge, discharge. For example, there\'s much more
recharge to the north of the site. Discharge is primarily to the south
in Death Valley and also in the Amargosa.

Other features that control flow in the site model are the local
geology, as Claudia pointed out, at the regional scale. You have the
spatial location of the different geologic units, their material
properties, and then there\'s also the role of faults which can change
that.

And, finally, on top of all this, then you\'ve got the local conditions
such as local recharge and what may be going on at Fortymile. So, these
were all features that were considered in the flow model.

In transport, several key features here to keep in mind. First of all,
we\'ve got potential radionuclides migrating from the repository, down
along the water table, out into the alluvium, and the Amargosa here.
Within the volcanics which is primarily the longest part of this flow
path, we\'ve got several different properties that we need to consider.
Those would be advection, of course, and matrix diffusion. Within the
matrix, we allow sorption to occur. In the alluvium, then it\'s
considered a porous medium flow system. And then, you have on top of
this, sorption can occur to the alluvium. In addition, there are
processes that we consider\--let\'s see, over here, down here, some
other processes would be radioactive decay, of course, because these are
radionuclides and then the role of colloids and how the transport of
colloids may influence the transport.

Now, what I want to show you is very briefly some of the results from
the site-scale model and then we\'ll get into some of the other lines of
evidence. You\'ve seen the left hand side of this picture before. These
are the flow paths that were calculated based on the calibrated
isothermal site-scale flow model. And, again, they start at the
repository, migrate to the southeast, and eventually are drawn into the
Fortymile flow system, and then head on to the south.

The other thing to point out here on the left side is a cross-sectional
view of those flow paths. So, you\'re looking from the side and we can
see here that again some of the flow paths because there is some
recharge a lot at the site, some of these flow paths do go down. This is
about 300 meters or so of displacement in the vertical. At some point in
the flow system, you see that the flow lines converge in the vertical as
they\'re going through a very narrow aquifer and they again spread out
as you get further to the south.

This is an example of some of the flow lines\--or these aren\'t flow
lines. These are transport calculations along the flow paths that you
saw in the last slide. These are breakthrough curves of radionuclides at
the accessible environment after release at the water table beneath the
repository. These breakthrough curves include all of the processes that
I spoke of earlier which would include the advection, diffusion, and in
the case of Neptunium, sorption. And, you\'re going to see more of this
information later in Bill Arnold\'s presentation, but I just wanted to
give you a flavor of the kinds of results that are coming out.

The left figure here represents the transport of radionuclides that are
considered conservative or nonreactive. So, it would something like
carbon, technetium, or iodine. And, these calculations were made
allowing uncertainty in model parameters including the specific
discharge as a result of different recharge scenarios and other model
parameters including the transport parameters.

Then, if you look over on the right side here with neptunium, it\'s the
same uncertainty parameters in terms of flow, but we\'ve added in a
moderately sorbing radionuclide, neptunium, and you can see the
significant difference that sorption makes.

Now, what I want to go over is the different lines of evidence that we
use to give us some confidence in these model predictions. And, I\'m
going to step to four different sources of evidence and I\'ll start with
the first two on this slide.

The first part of this is correspondence to measure data and that\'s
both through the calibration process and through something that we\'re
calling validation. But, during calibration, of course, the model is
matched to observe potentiometric data and we use also hydraulic
conductivity data. So, as we\'re adjusting hydraulic conductivities in
the calibration process, we\'re comparing back to our measured hydraulic
conductivities.

If you look down at the bottom here, when I say correspondence to
regional observations, this represents the boundary fluxes that Claudia
presented earlier. And, what we were using in this calibration of the
flux is from the 1997 regional model. We did not calibrate to the later
versions. If you look at the calibration data for heads and conductivity
and the fluxes\--and those aren\'t going to be presented just here
really as a matter of time, but the calibration was actually pretty
close. In other words, as you would expect, the modelers kept working
with their model until they got the calibration parameters to match
closely to what was measured. And, there\'s really no surprise there.
And, I don\'t really consider the calibration data truly independent
lines of evidence because, in fact, you use that in the modeling
process.

However, we do have some validation data. This is information, for
example, water levels in the Nye County wells. During the calibration,
we had some water levels in some of the wells, but during that process
and afterward, other wells were drilled and other water levels were
collected that were not used during the calibration. So, we can compare
our model predictions to water levels collected after the fact as a way
of checking to see how well we did in our simulations. The other thing
we did is we have some cross-hole hydraulic conductivity data from the
Alluvial Testing Complex which again was down near Fortymile Wash near
the compliance boundary or the accessible environment. That information
was collected after the calibration, as well.

The other two types of evidence that I will present, the first is
corroboration with hydrochemistry. We looked at the water chemistry in
actually the whole Yucca Mountain region and used that to assess
potential flow paths looking at either the chemical evolution or,
depending on the particular isotope, the lack of evolution as an
indicator of flow paths. Used that information to address mixing of
different water types and, in fact, depending on if you look at
something like carbon-14, you may be able to get some sense of how long
the water has taken to get from the land surface to its present
location. You\'re going to see more of this type of information later
this afternoon from Gary Patterson.

Finally, we also looked at groundwater temperature. We did some what we
call validation simulations where we tried to simulate the temperature
of the groundwater and to see how well we did again because temperature
is somewhat independent of the flow process. You can look at that
information, as well, to get some credence to your calibration.

So, let\'s start off by looking at the new water levels that were
collected at the Nye County wells. This is Highway 95 to the south. The
values that I\'ve listed here in the blue represent the water level
residuals, the difference between the calibrated value and the measured
water level. These were obtained during the calibration. So, this is
data that we had at the time of calibration; here, over here at the
Washburn Well, Well #2-D, and several of the wells up here to the west.
The data in red represent water levels that were either measured later
in different completion intervals than we had earlier or in wells that
were drilled after the calibration was completed.

And, several things I want to point out in here. If you look at this
region down at the bottom of Fortymile Wash, there are certainly
differences between what was measured and what was observed, but the
magnitude of the differences here based on this new water level data is
in the same range as what we saw during the calibration. So, in other
words, we weren\'t getting any surprises from that. As we moved further
to the west, you can see that the difference between measured and
observed values is increasing. We\'re not doing as good a job of
matching observed water levels, but again they\'re in the same range as
the calibration. So, in other words, the new water level information
isn\'t showing us anything we didn\'t know already. So, that gives us
some confidence in what we had earlier.

Another piece of data is the hydraulic conductivity values from the
Alluvial Testing Complex. There was a cross-hole test conducted at the
Testing Complex after the calibration in the alluvium and we obtained a
value of the permeability, intrinsic permeability, of 2.7x10^-12^ m^2^.
That value is 19 percent lower than what we used in the model. So, the
model was using a slightly larger value. But, again, we didn\'t have any
measured conductivities in the alluvium down here at the time. So, this
was actually a pretty good fit.

If you take the water levels that were measured at the ATC, the Alluvial
Testing Complex, and the new hydraulic conductivity and calculate what
the Darcy flux would be, you\'ll find that the model calculated Darcy
flux at that location at about 27 percent larger than what we get from
the data after the fact.

The third line of evidence that we can use to give us some confidence in
our model predictions is the hydrochemistry. And, again, Gary Patterson
will be presenting much more detail on this later, but what I want to
show here are the red lines or the red arrows which represent flow paths
that were obtained based on looking at the water chemistry data. Then,
over here, you\'ll see the black lines represent the model predictions.
And, in general, we see that there\'s a pretty good correspondence that
the chemistry does support the calculations that were made based on the
hydraulics.

Another aspect that we looked at with the water chemistry, we did a
chloride mass balance approach to estimate what the recharge rate might
be, particularly in some of the wells in the northern part of the model
area. And, based on that mass balance approach, estimated the recharge
somewhere between 7 and 14 mm/yr. Now, the calibrated model uses a
recharge rate of about 4 to 5 mm/yr. If you recall from the
presentations yesterday, the unsaturated zone studies, they estimate
that infiltration rates somewhere in the range of 1 to 11 mm/yr. So,
again, this chloride mass balance approach gives us recharge values that
are in the same, really pretty close, or maybe slightly above the value
that was used in the calibration.

And, I did want to point out that, at least, in the version of the model
that we were doing, the entire site-scale model recharges less than 5
percent of the total flow through the whole system. We have much more
boundary fluxes than we do local recharge, at least, in the version that
we were using.

The last set of data I want to talk about is this what we called
validation-thermal modeling. And, what we were doing here, we were going
to model the distribution of temperature in the saturated zone assuming
both conduction via the natural geothermal gradient and convection
caused by groundwater movement. And, this was done in two steps.

The first step was to look just at thermal convection. So, we didn\'t
allow groundwater flow. It was simply a thermal model. So, you allowed
heat to rise up through the different geologic units. We had different
heat properties, different thermal conductivities for the different
units. We took into account the topography, etcetera. Then, calibrated
that convective model and what we found is that we had 94 observations
of temperature in 35 wells, temperature ranged from 22 to 62 degrees
Celsius and we were able to account for 80 percent of the variability in
temperature with this conduction model alone.

On the right is a figure that shows the residual difference between the
calculated and observed temperature from this conduction model. And, you
can see that, in general, most of the observations fell within a range
of roughly -6 to +6 degrees C.

Then, we did a second step where we took that calibrated conduction only
heat model and combined it with the calibrated isothermal flow model
which I presented earlier and we used those two pieces of information to
define specified pressure and temperatures at the boundary of the model
area. Then, we did a coupled heat and flow simulation and ran that to
steady state. Now, what I want to point out is we did not make an effort
to dual calibrate that model. It was simply one run, did an independent
heat conduction model and essentially an isothermal flow model. Even
without calibration, we were able to obtain 85 of 94 observations within
10 degrees Celsius; not a great fit, but it isn\'t terrible, as well.

This figure on the left represents the temperature residuals based on
the conduction model alone without groundwater flow. What we can see in
here is to the north and out here primarily to the west, even a little
bit to the south, the model is under-predicting temperature and this is
temperature at the water table. So, what this is showing is that the
conduction model is predicting temperatures a little lower than it
should be in this region and then it tends to over-predict temperature a
little bit right here at the Yucca Mountain site itself. When we bring
in the effect of groundwater flow, in some areas it doesn\'t change
much. For example, in the north, there isn\'t much of a difference, and
over here all the way to the south, there\'s a little bit of a
difference. But, we do see a difference here in the region of the site
where now in some cases, especially to the south where we may have been
under-predicting before, we\'re over-predicting a little bit now. What
this shows us is that there clearly is an impact of the groundwater
flow. The groundwater does and can change the temperature distribution
that you would have gotten from the normal geothermal gradient. But,
even without calibration, we\'re still getting, I think, a match to
observe temperatures that are reasonably good.

So, in summary, what I want to talk about is that we had multiple, what
we believe, are independent lines of evidence to corroborate the
calculations of the site-scale model and increase our confidence in
these models. We looked at calibrated data; water levels, conductivity,
and boundary fluxes. But, again, those aren\'t really independent
because you would expect those to be matched pretty well. We have some
validation data; new water levels and new hydraulic conductivities that
weren\'t available at the time of the modeling. The hydrochemistry which
was an independent way of looking at the water information. So, we
didn\'t use the hydraulics; we were using the chemistry. And then,
finally, the thermal information which is going to tell us something
about vertical flow probably more so than horizontal flow.

So, I\'m done.

NELSON: Thank you, Ken.

Can you tell me\--this is Nelson, Board. Is your water moving in the
fault predominately, the fault zones, or is it moving through tertiary
volcanics as fracture flow or by whatever, predominately?

REHFELDT: Yeah, it\'s primarily through the tertiary volcanics through
this dual porosity medium. And, we have some faults in there, but
they\'re primarily barriers to flow; Solitario Canyon, the Highway 95
Fault. There is a structural zone which could be a fault that\'s in the
model under Fortymile Wash which, of course, is more of a conduit.

NELSON: Okay. Questions? Dan?

VAN GENUCHTEN: In the sense\--van Genuchten.

BULLEN: Oh, I\'m sorry.

NELSON: I think the problem is when I say Dan, it\'s also van, van
Genuchten. Can you wait, Dan?

BULLEN: Sure.

NELSON: Okay, thanks. Go?

VAN GENUCHTEN: On Slide 7\--van Genuchten. So, on the lines of the
earlier question, the one breakthrough there after 10 years, what\--you
know which pathway that went?

REHFELDT: No, I don\'t\--I couldn\'t tell you exactly what pathway that
was. I don\'t know if it\'s a fair question to pass off to Bill Arnold,
but Bill will be presenting these results, among others, later this
afternoon.

VAN GENUCHTEN: Okay.

NELSON: Bullen?

BULLEN: Bullen, Board. There\'s always a risk with giving backup slides
because, you know, some of us actually go and look at them. So, if
you\'d go to Slide 22, I just have a quick question. Based on the
results that we saw this morning from the new regional scale model,
could you explain the results that you see here and, in fact, I like the
fact that you actually gave us some real flux numbers here. So, I was
just wondering if you could summarize the results here and say how do
these relate to what we\'ve heard already in previous presentations?

REHFELDT: Okay. To start out just to give everybody an explanation of
what\'s shown here, this again is the site-scale model boundary. When we
were doing the calibration to the regional fluxes, we actually broke
that boundary into a series of segments. So, these different red and
black regions represent the different segments. So, we calibrated to
those segments individually rather than just to the entire model
boundary. But then, over here on the right, what I\'ve done is I\'ve
summarized the comparison between what came out of the 1997 regional
model and the values that we obtained from the calibration summed over
the whole boundary. So, I think what you\'re asking is knowing that
these particular boundary fluxes, say, summarized over the whole
boundary have changed substantially between the \'97 version and 2002,
and of course, the current transient version.

A couple of things I want to point out in here. We are currently doing
an alternative model calibration with the site-scale model using the
2002 boundary fluxes. So, we\'re using the updated geology at the
regional scale and the updated boundary fluxes. So, we will by the end
of this fiscal year have a comparison for that, as well. So, we\'ll be
able to see what the differences are.

Another thing to point out here along this eastern boundary. What you
see is that the majority of the flux in the \'97 model was down here in
the southeast corner. That comes from a little triangle of carbonate
rock that was in that version of the regional model. And, what\'s
happening here is you\'ve got water coming into the carbonate from the
east, bypassing that corner, and going out the south. So, you see larger
fluxes through the south and from the east, but it\'s really just flow
in the carbonate down here in this corner and it doesn\'t impact much,
at all, the flow that we see coming off Yucca Mountain and into the
alluvium above it.

So, I don\'t know what the results are going to be later this year,
although I would expect that we probably won\'t see tremendous
differences between this version and the newer version because, you
know, a lot of this boundary flux difference is beneath the flow system
of interest.

BULLEN: Thank you.

NELSON: Okay. Ron?

LATANISION: Latanision, Board. I should just preface this comment by
pointing out the symmetry in what I\'m about to say and that is that
since we\'re talking about the saturated zone and I\'m personally
beginning to feel a little bit saturated on the information, this
question may be a little odd, but I want to make sure I have the
perspective clear. If we could turn to Slide 7, if we were to look at
the equivalent breakthrough time for water as opposed to radionuclides,
am I correct in my impression that we would find that water is likely to
rise before the radionuclides and the breakthrough time for individual
radionuclides may be a function of such things as their own transport
characteristics and ion interactions or colloid interactions or maybe
magnetic fields or whatever? Do I have the correct perspective or am I
missing a point here?

REHFELDT: I guess I\'m not quite sure how to answer that question. I
know and I think you got\--the second part of that is, yes, for each
individual radionuclide, you\'re going to have differences as a result
of the size of the molecule and its diffusion characteristics, in
addition to how it might sorb or not sorb to either colloids or the
aquifer material.

LATANISION: Yes.

REHFELDT: As far as the transport time of water, I think that\'s a more
complicated problem than it first appears. You still have this whole
issue though if you think of tritium as representing water because it
can be part of the water molecule. I mean, the transport of tritium
itself has some complexities because of diffusion in and out of the
matrix. So, I\'m not sure really how to answer your question in terms of
really what is the velocity of the water itself.

LATANISION: Latanision, Board. There\'s a temptation to think and maybe
it\'s a zero order expectation that if water is transporting these
radionuclides that when water appears, radionuclides appear. All I\'m
thinking is that that\'s not necessarily\--in fact, it\'s obviously not
the case because the transport of the radionuclides is going to be a
function of a lot of variables that are different than\--

REHFELDT: Right. Yes, it wouldn\'t necessarily\--this is not necessarily
representing the velocity of the water.

LATANISION: Right.

REHFELDT: Yes, that\'s correct.

LATANISION: Thank you.

NELSON: Thure?

CERLING: Cerling, Board. If we could go to Slide 16? So, you sort of
have two scenarios here, one of which you include the convection and one
which you don\'t include the convection model for heat. And, some of the
circles, a lot of the circles, are still between 3 and 10 degrees
Celsius off and some of them actually switch signs and are now in the
opposite direction.

REHFELDT: Yes.

CERLING: How do you anticipate using this information to improve what
you have or can you use this information?

REHFELDT: No, I think we can use this information. One of the primary
effects we\'d expect to see from flowing groundwater in a situation like
this, if you have essentially horizontal flow of water with sort of a
natural geothermal gradient, you really don\'t expect to see\--at least,
I wouldn\'t expect to see\--much of a disruption in that geothermal
gradient. And, where I see large differences between the water
temperature indicates, at least, to me it\'s more of an indicator of
vertical flow influences or potential vertical flow influences. So,
either downward flow of recharge or upward flow of warmer water will
disrupt that geothermal gradient. So, I think that using the temperature
information gives us more confidence in how we\'ve characterized the
vertical flow than it will in how we characterize necessarily the
horizontal flow.

CERLING: Okay. Well, I mean, just to follow on that, do you anticipate
using this to significantly improve your understanding of the flow paths
itself or is this kind of just going to be used as a calibration or a
validation of the model?

REHFELDT: At this point, what we\'ve done is to use it to give us a
little more confidence. If you look at the flow paths that I showed
earlier, they\'re primarily horizontal. There\'s a little bit of
vertical movement and then these things tend to skirt along near the
water table. What we were using, the temperature information, was to
help us and give us confidence that, in fact, we weren\'t missing
something that might indicate a significant vertical movement either
upward or downward. You know, the overall temperature range in this
system is around 40 degrees Celsius. So, if we had significant and rapid
downward movement or upward movement somewhere, I\'d expect to see much
larger temperature differences than what we\'re seeing here. That\'s
what it was used for.

NELSON: Okay. All right. We have three more; Richard, Frank, and then
Leon.

PARIZEK: Parizek, Board. I like the approach of trying to pull all the
pieces together with all sources of data. That sort of helps on one hand
with the calibration confidence building, but also where you can, you
add to the validation process and you\'ve shown us a whole range of
approaches that were used. I was just rummaging through my pile for the
technical basis document that talks about Figure 19 or, at least, gives
another alternative. So, if you could go to your 19 here? There\'s an
interpretation that the model result is on the right. The observed
contouring is on the left. But, in the technical basis document,
there\'s another interpretation of contours of head that look more like
the model simulation. The comment here is that you have the finger-like
projection at that 775 contour. You know, it\'s off in the\--it\'s a
long nose that comes down\--

REHFELDT: Are you\--

PARIZEK: To the left, to the left, to the left.

REHFELDT: Oh, down here.

PARIZEK: We have a ridge in there.

REHFELDT: Okay.

PARIZEK: And, conceptually, that ridge requires some interpretation.
One, it might be the result of contouring, say, perched water in which
case the ridge doesn\'t exist here. It would look, more or less, like
the contours on the right. And then, also, another interpretation that
was drawn based on head data, not the model runs, but the actual
interpretation. Then, that would ask for higher permeability patterns
that might be dammed to the south, east, and west with flow concentrated
and then kind of locked in, sort of like leaking under a dam. Another
possibility would be higher recharge rates in that area relative to the
areas on either side, same permeability or lower permeability east and
west of that ridge. But, in any event, there\'s different ways to look
at this. And, you say, well, how can I get a ridge like that in the
conceptual model? I mean, it requires some permeability effects in the
system. And, there are two fault zones that are either side of that
nose. And, damming on the nose could be the Highway 95 Fault on one
hand; there\'s also volcanics in that area, the basaltic units, that
could also be lower permeability. So, I just need\--either the nose is
there or it\'s not there. If it\'s not there, well, then your model
simulations come out looking better. If it is a nose, then the model
simulation has missed it and conceptually why does it miss it?

REHFELDT: Well\--

PARIZEK: What do we do about that?

REHFELDT: Well, I guess, what I want to point out here is that this
version of the observed water levels was a contouring that we did just
based on some of the observed values and was machine contoured. So, I
think, some of what you\'re seeing in here is an artifact of
concentration of a couple of data points right down in here and then
very little data above it. And, what I really should have used here was
the contour map that was developed by the U.S. Geological Survey to
represent all of this information. So, I think\--you know, I may be
misleading people because I don\'t think this represents what would be
the general consensus for the water table. This was done primarily just
to give us a general sense, are we capturing the same general directions
of flow from the model, but wasn\'t intended to look at specific
contours. So, I don\'t think\--or, at least, I don\'t believe that we
consider this to be a definite feature that we had to calibrate to. I
think it\'s an artifact of the contouring.

PARIZEK: Parizek, Board. It does, nevertheless, represent one
alternative interpretation. And, given the fact you have two and then
John Bredehoeft reminds us how easy it is to sometimes get caught up in
one and say, well, maybe they\'re equally likely. Unless the program can
really throw out this one on the left for legitimate reason\--it\'s just
like the chloride-36 thing. You can\'t just throw it away now. You\'re
got to sort of convince yourself that there\'s error or there\'s some
difficulty with the dataset. Right?

So, here, if it\'s perched water and it\'s based on that, that\'s one
thing. If, on the other hand, it may be a coequally useful
interpretation, it gives you an alternative model. It\'s a groundwater
ridge and it has a divide in it and then you can create\--I have about
five different ways I can create it conceptually. Then, I say, well, I
think I have to track it down and eliminate each of the alternatives
before I can feel good about it because it does affect flow or could
affect flow if, in fact, that\'s the correct interpretation.

So, with all of the other contributions that were made through the
review showing all the different lines of evidence you use, this is one
that sort of jumps out begging for some interpretation. If you throw it
out, you\'ve got to justify doing so. Okay?

REHFELDT: Okay.

PARIZEK: Or if the program throws it out.

NELSON: Okay, thank you. Frank and then Leon.

SCHWARTZ: Schwartz. Could you go to Slide 7, please? Ken, one question I
had about Slide 7 there on the left panel where it looks at, say,
carbon, technetium, and iodine, there\'s one breakthrough curve that\'s
really short there, you know, 10 years. What conditions in the model
actually have to come together to produce that fast a breakthrough?

REHFELDT: Let\'s see, I\'d actually have to defer to Bill Arnold to give
you the exact answer. I mean, in the general sense, what you\'re
probably looking at is the tails of a whole series of distributions; you
know, the most rapid velocity, no diffusion, or very limited diffusion,
things like that, maybe the smallest porosity that was in the
distribution range, etcetera. And, you start combining all of those
things together and you can get what really turn out to be physically
impossible results.

SCHWARTZ: Okay. The second question I had was it looks like the\--you
know, just looking at how black it is in the density of curves there on
the left hand side, it looks like most of the breakthrough curves are
between 100 and 1,000. Is matrix diffusion turned on for the transport
through the fractured rock part? It seems like\--

REHFELDT: It is.

SCHWARTZ: It is?

REHFELDT: Yes.

SCHWARTZ: And, it seems relatively ineffective, one would think\--I
mean, in performance assessment, for example, one of the ways they get
similar breakthrough curves is this idea of saying that the rock blocks
are very big and that flow is through a very select group of fractures
and matrix diffusion and that setting doesn\'t have an opportunity to
work very well. I would think your model is constructed differently and
yet you\'ve got similar results. And, I wondered have you tried to
capture this idea of flowing intervals somehow in your model or\--

REHFELDT: Yes.

SCHWARTZ: I mean, it\'s not obvious it would be here, but I wondered how
you\'ve captured that and that\'s where I\'m going here.

REHFELDT: Yes. This afternoon, Stephanie Kuzio is going to be presenting
some of the transport parameters and how those were conceptualized and
the distributions we used and she will\--one of the parameters that
she\'ll talk about is the flowing interval spacing which I think is
exactly what you\'re getting at. It\'s how far apart are the actual
flowing paths, not just the fracture itself.

SCHWARTZ: Thank you.

NELSON: Leon?

REITER: Leon Reiter, Staff. This question may in some part be due to my
large problem of misunderstanding. Could you put on Slide 13, please?
The bottom bullet sort of gives the impression that local recharge is
not that important. It\'s a very small amount. I\'m thinking back to
what Jim Winterle said where there are a very small amount of local
recharge coupled with, I think it was, the lower porosity that resulted
in some rather large changes in travel time, shortened travel time. So,
is there a difference of opinion here? Did you take into account\--I see
you took into account local recharge. Did you take into account changes
in porosity in a volcanic aquifer?

REHFELDT: Well, first of all, I\'m not sure on terms of the porosity.
You know, I apologize for that, but I don\'t\--I think it was just a
constant porosity for the\--no, it wouldn\'t have been because the
porosity would have been variable, as well. There will be more
information on that this afternoon. Bill Arnold will be presenting those
same breakthrough curves that I showed earlier, among others. So, I
think he will address that question in more detail.

To get to maybe another point, the bottom bullet there represents the
particular calibration or set of model runs that we did for the flow
model. You recall that we used the 1997 regional fluxes and they were
quite a bit larger than what are coming out of the more recent regional
simulations. So, I think that this comment which is correct for the
version of the regional model we used may not be correct when we start
looking at the more recent fluxes because the proportion of boundary
flux to recharge will change.

REITER: So, Bill Arnold is the appropriate person for this?

REHFELDT: I think, if you want to get questions related to the
parameters, the porosity, etcetera, yes.

NELSON: Okay. Thank you, Ken.

Okay. We\'re to that period available for public comment. I\'ve received
a sheet of paper that has four people listed and I just want to make
sure that these four people are here and that they need to talk now as
opposed to at the end of the day.

The four people are Atef Elzeftawy, is he here? Yes, of course, he is.
Sally Devlin, Matt Kozak, and Judy Treichel. So, is that true you all
need to talk now and not the end of the day?

TREICHEL: No\--

NELSON: Judy can wait. Okay. That just gives us a little bit of
flexibility.

We\'re on schedule. We have about 20 minutes. What I\'d like to do is
ask you to keep your comments to five minutes, and at five minutes, I
will stand up and walk towards you and stand quietly behind you. That\'s
a subtle indication that five minutes is up.

So, perhaps, we could go through in sequence as I read them. So, first
up is Atef Elzeftawy, I\'m trying, from the Las Vegas Paiute Tribe.

ELZEFTAWY: Well, you can call me Osama bin Laden. That\'s\--

NELSON: I don\'t want to call you that.

ELZEFTAWY: I\'m not going to take the five minutes, but you know, it\'s
funny that Osama bin Laden highjacked the Moslem religion, George W.
Bush highjacked the surplus, and the Department of Energy with the
modelers highjacked the science of this site.

If you haven\'t read the book that was published by James Watson about a
couple of months ago entitled [DNA]{.underline}, I think you need to buy
it and read it. It\'s about \$65 a book and he, in it, lists the things
when he got involved 50 years ago about the DNA analysis and the DNA as
it went through in 1953 until last year, 50 years anniversary. In it, I
think, there\'s one thing to remind me when I left the University of
Illinois and the bad Marty Mifflin brought me here to introduce me to
the arid climate is that science and politics mix quite well. Before
that, I thought science and politics, like oil and water, they don\'t
mix.

And, I think, these are just food for thoughts for you guys. I know that
you want me to get out of here. You\'re hungry and you\'re tired and you
need to go. But, as I look back, I think, I see a lot of similarities
between all these activities. I wish we had the money available to the
science that now we know that we have unsaturated flows more than 1
mm/yr. And, I remember Marty and myself back in 1982 when we decided
that it should be more than 1 mm/yr just by the back of the envelope
analysis and me, as a physicist, and he, as a hydrogeologist in terms of
the Yucca Mountain thing. And, the DOE at the time insisted at the time
that it\'s 1 and it\'s matrix flow. They submitted the EA, environmental
assessment, to the NRC and they insisted it\'s 1 and matrix flow. It
took the Department of Energy, what, 15 or 16 years to be able to
say\--I don\'t know why they took that long to learn the language\--it
took them that long to say that it\'s more than 1 and there\'s a
fracture flow. And, that\'s awfully sad. I think the benefit we got out
of that is that list of those people who got employed for the last 10
years to provide us with that little comment.

I want to go back to this [DNA]{.underline} book because in it we had
two players. One of them, Linus Pauling with his (inaudible) prize and
his arrogance\--sorry about that\--or ego and then this James Watson,
the guy who was just 24 or 25 years old opened things. It\'s the
attitude again. Linus Pauling was working on the DNA and Bragg and his
people was working on the DNA in Cambridge. And, you cannot divide three
chains by two and you come up with one and one in a sense. Linus Pauling
had this conceptual model\--again, remember a conceptual model of three
strands of the DNA\--and this James Watson and (inaudible) over there,
oh, it should be only two based on all the data. Remember the data
information they had. What Pauling did is what we do today; we just get
the data we have and mix it together and finish the model and we make
these little crooked lines and so on. Well, he didn\'t get it. And, one
day, Watson sat down and he just was worried about his story, worried
about all these things that he\'s doing and the model, and finally he
got the cardboard and put it together and he got it.

The amazing part of that is that you cannot model the DNA. We know today
that if you flip from one base to another, either you get sickle cell
problems in your hemoglobin or you don\'t get it. It\'s 1 out of 3
billion base. Now, how can you model that? That\'s my critique to the
performance assessment of the DOE. What may go wrong in terms of finding
out what is happening in the basic part of the science? So, just think
about that. Think about we put all our eggs into this kind of a basket.
I think, that\'s hard to do.

She\'s going to kill me now. So, on behalf of the Las Vegas Paiute
Tribe, thank you for coming. Come back again to Las Vegas. It\'s good to
have everybody here and I think that\'s the comment of the Chair for you
guys to come. So, it\'s better than going to Washington, D.C. It gives
more people visibility and gives you more visibility and that\'s on the
site. So, come back again.

Thanks for your time.

NELSON: Thank you, Atef.

ELZEFTAWY: Thank you for not hitting me.

NELSON: Next up is Sally Devlin, public.

DEVLIN: Good morning, everybody, and again, as always, thank you so much
for coming to Nevada. I hope next time it\'s in Pahrump or close to
Pahrump.

Anyway, what I wanted to talk about today is a comment that really
echoes what was just said. And, I was very disturbed yesterday by the
report on the Mojave Desert. And, I asked the man why did you do it on
the Mojave Desert and he said that\'s where I had the money from. Now, I
don\'t think that\'s a good sign. That\'s when our area needs the
science. And, of course, we\'re 2,000 feet higher than the Mojave Desert
and we\'re a very different desert. So, I don\'t think that really
affects Yucca Mountain.

But, the reason I asked these wonderful men here to put up the slide is
I\'m going to talk about Nevada. When I had the last meeting here, I
said Nevada\--and I apologize to everybody\--was the bottom of the
barrel. Well, we\'re really only 49. But, the reason we\'re #49\--and
I\'m going to give you another reason for it\--is in the middle of this
thing, everybody can see the boundary between Nevada and California.
That line is called the Von Schmitt line. That line was created based on
the 1823 Mormon marches from Utah to Los Angeles. This line was done in
1872 and it\'s called the Von Schmitt line.

Now, the next line I\'m going to tell you about is Clark County. Clark
County where you\'re sitting right now is using an 1881 boundary survey
map. The State of Nevada never had a boundary map until 1979 when two
convicts said we don\'t want to be in an unbounded state, and therefore,
they had to go through two sessions of the legislature and remember we
only meet every other year. And so, in 1982, they got a boundary map.
But, they didn\'t bother to check the boundaries. And so, you\'re
looking at a line that was done in 1872.

Now, what\'s interesting about it, back in the \'70s when I lived in
Reno, they had a conflict because the State of California said we own
Lake Tahoe and State Line. So, they had to go and measure the Von
Schmitt line from Lake Tahoe all the way up to Oregon. This line goes
all the way down south to the Colorado River.

Now, the reason I\'m telling you all this nonsense about boundary lines
and so on is on this particular map which really was wonderful because
you know I love my friends from Inyo is you\'re seeing the size of the
boundary which I doubt has ever been bounded or surveyed even by global,
what do they call it, positioning. And, it really kind of bothers me
because for the last nine years when I found out Pahrump does not have a
boundary map that has been surveyed, we have had problems.

Now, the only reason I\'m bringing it up and I think it\'s a question
that\'s never come up is you see how out of step Nevada is and
well-deserving of our #49 status. Of course, one mapping is the main
thing and that\'s why I\'m here for this hydrology learning session and
that is supposing the water crosses that make believe line of Von
Schmitt\'s from 1872? Who is going to sue who? Now, supposing the water
from California from Inyo goes to Amargosa and kills 15,000 cows?
Supposing all this stuff works together and who is going to sue who and
on the length of time and so on? So that unless you realize we do have a
social problem and I really think it is a social problem that something
has got to be thought about it and done about it.

I do not believe that this 10,000 years that you\'re talking about
monitoring Yucca Mountain\--and, of course, Abe and I will be sitting on
top of both Yucca Mountains playing gin rummy\--I don\'t think 10,000
years\--and you\'re seeing it with the neptunium and so on\--well,
you\'re talking 100,000 years. I think that Yucca Mountain should be
monitored for, at least, 200,000 years. I think more should be noted on
the millirems coming out and the exposure to the people and so on.

Of course, if the volcano blows or my Ingrid blows and you know that
Amargosa\--that the ash can\'t go to Pahrump or Beatty or Death Valley,
and of course, my concern on all this stuff is it does go to Death
Valley. And, Death Valley is our national monument and you\'ve heard me
say for years you can\'t kill (inaudible). Well, what you\'re teaching
me is that that line, that imaginary 1872 Von Schmitt line, can be
penetrated from both sides maybe.

And so, I think, it\'s rather important that you do look into this and
realize about the mapping and the boundary lines and the State of Nevada
is in big trouble because of this and I don\'t want my friends here to
get in trouble either.

Thank you.

NELSON: Thank you. Third up, Matt Kozak from Monitor Scientific?

KOZAK: I appreciate this chance to talk to you. I am actually here
representing the EPRI TSPA team. And, the reason I came up here, I
actually hadn\'t intended to talk to you, but I started hearing some
things creeping into the conversation that I thought ought to have some
discussion and it was really crystallized in some of John Bredehoeft\'s
comments on philosophy.

Really, the point that I wanted to make sure that we don\'t lose track
of is that there is a fundamental difference between the scientific
uncertainties and the regulatory uncertainties and they are addressed in
quite different ways. John talked about validation and the importance of
validation and history matching and so forth. There was a raging debate
about 15 years ago in the waste management community on this whole issue
on the people that follow Carl Pauper\'s theory and those that follow
Thomas Kunz\' theory. We\'re at screaming matches at these meetings.
That\'s pretty much been laid to rest about 10 years ago and this is not
just DOE/NRC kind of coming to an agreement. This is internationally
people have come to a very consistent philosophy on how these things are
done in highly developed confidence. So, I don\'t think we ought to lose
that in this discussion. We don\'t want to go back 10 years and start
talking about validation again. There\'s a reason why validation does
not show up in some of the DOE and NRC documents. They talk about
confidence building and things like that. There\'s a very good technical
reason, a number of technical reasons, for doing that.

The second point that I picked up was on the treatment of alternative
conceptual models. Again, this is not something that is particularly
new. This has been an intrinsic part of the waste management community
for, at least, 10 years. I know I was publishing stuff on it 10 years
ago and I was citing prior work. So, there\'s a good body of work, good
body of literature on that whole topic and on how to resolve conceptual
models or alternative conceptual models. It\'s an intrinsic part of\--if
you look at the DOE TSPA documents, they\'re required to consider
alternative conceptual models. It\'s part of the license review program
for NRC. It\'s a basic part of the NRC\'s review process. So, again, I
don\'t think we ought to get off on the wrong track of thinking that
this is something new or something that\'s outside of normal experience.
It is not typical of scientific approaches to modeling. It is typical of
regulatory approaches to modeling.

In addition, as part of the resolution of those alternative conceptual
models, we also need to keep in mind that there is a forward program on
confirmatory evaluation and additional data collection and so forth that
allows us to address any residual uncertainties that may be important to
safety.

So, finally, I\'d just like to say that one of the other comments was on
modelers reviewing their conceptual models as immutable. If you think
back over the last few days, we haven\'t seen a single immutable model.
They\'ve all been evolving, they\'ve all been changing, and very open to
change and considering alternative conceptual models and trying to come
up with the best safety-based case. The one idea that I did like was
that all this modeling has to be directed toward robustness and
robustness needs to considered in terms of overall system safety, not
simply in terms of the influence of some residual scientific
uncertainty. So, if we can keep the idea of how the overall system
responds to these uncertainties in terms of safety, I think if you keep
that clearly in mind as you go through your deliberations, I think that
would be of great help to you.

Thank you.

NELSON: I ask Judy Treichel if she wants to comment now or to hold?
She\'s going to hold, okay.

In which case, we are two minutes before our chartered time for the end
of this session. I thank all of our speakers and all of you for
participating. We will begin the next session at 1:15 on schedule.

(Whereupon, a luncheon recess was taken.)

[AFTERNOON SESSION]{.underline}

BULLEN: I\'d like to welcome everybody back to the afternoon session.
Please ask you to grab your cup of coffee, grab a seat. I\'d
specifically like to have my Board members back, if I can find them.
Okay, the entire board back.

Good afternoon. I have prepared remarks, which I\'ll read, and then I\'m
going to do a little extemporaneous speaking. Welcome back to this
afternoon\'s meeting of the Board Panel on the Natural Systems. I\'m Dan
Bullen. And, contrary to what it says in the agenda, I am not a member
of this Panel. I could be ex officio. This might be one of the few
panels that I have never been a member of, but I still enjoy
participating.

Having said that, I will be chairing this afternoon\'s session, and this
afternoon, we\'re going to continue with the theme of saturated zone
fluid flow and radionuclide transport. If you can recall from this
morning, that we were presented with a list of questions and outlines of
the central purpose of the entire two day meeting. Each of these talks
this afternoon will address one or more of the aspects of those
questions.

The first talk this afternoon will be presented by Gary Patterson of the
U.S. Geological Survey\'s Yucca Mountain Project. He will discuss
geochemical mapping of the groundwater system, and what the
interpretation of that geochemistry can tell us about the waterflow in
the saturated zone.

The next presentation will be by Stephanie Kuzio, of Sandia National
Laboratory, who will discuss the transport processes of sorption, matrix
diffusion, and colloidal facilitated transport, and how those are
represented in DOE models.

At that point, we\'re actually going to move the break. We\'re going to
put the break at 2:20 this afternoon, and that\'s up from 3:10, and
we\'ll have the break just prior to the last talk presented by Bill
Arnold from Sandia, who will discuss the modeling predictions of the
transport of radionuclides through the unsaturated zone, and how those
predictions are abstracted for the total system performance assessment.

Now, following the presentation by Bill Arnold, we had originally
schedule a roundtable discussion, but at the present time, DOE elected
not to participate in our roundtable discussion, so we still value the
opportunity for technical discussion, and input into the process, so
what we have decided to do is change the format of this afternoon\'s
session. What we\'re going to end up doing is have essentially an open
forum. That open forum will allow for the discussion of the materials
that have been presented during the course of this meeting, both
yesterday\'s presentation and today, and we\'ll actually provide input
from our consultants, members of the Board who are here, the Panel who
are here, and members of the audience who may wish to participate.

I\'m going to facilitate that discussion or that open forum, and we have
identified a 90 minute time frame, at which we\'re going to continue
this work.

Now, I understand Dr. Parizek is going to give a few opening remarks,
and, so, I\'ll put the pressure on him now to realize what he\'s going
to say at that time, and we\'ll have our consultants also make a few
opening statements. But, then, we would invite any member of the
technical community, or the public in the audience, who would like to
make some comments with respect to the issues that were raised, either
in the five questions, or other issues that are associated with
unsaturated zone or saturated zone transport to come forward to the
microphone, and to make their comments known.

If there any questions about that, we can discuss it at the break. That
will happen before the meeting\--or before the open forum.

with that, I\'d actually like to mention one more thing. We\'ve been
very good at it so far in the meeting, but I\'d like you to silence your
cell phones so that we don\'t have any interruptions for our speakers
this afternoon. But, I\'d like to call Gary Patterson forward for the
first presentation of the afternoon.

PATTERSON: I think I should start off by apologizing in advance for not
having the results of the numerical model to present. But, I do mention
modeling a couple of times, so I hope you\'ll let me into the club
anyway.

Primary objectives of the saturated zone hydrochemistry and isotope
program at the USGS use major and minor dissolved ions, stabile
isotopes, radiogenic isotopes, and both inorganic and organic carbon 14
ages to determine flow domains, flow paths, identify discharge sites,
and estimate flow rates.

We intend to independently validate flow paths generated by saturated
zone flow and transport models, and independently constrain flow rates
generated by saturated zone flow and transport models. That\'s my
reference to modeling.

When we began this effort a few years ago, the first thing we did is we
constructed a series of isopleth maps or concentration plots of the
major ions in the system, just to get a first cut at what the system
looked like. And, when we did that, several things became apparent. The
first thing that becomes apparent, if you\'ll look at the sodium
concentration plot on the left-hand side, can everybody see that, the
first thing that became evident was this long plume of low sodium
concentration that\'s propagating beyond the Fortymile Wash system, and
then slightly elevated sodium concentrations in the Yucca crest,
elevated concentrations in the Oasis Valley, and another low plume of
sodium concentrations in the Crate Flat area.

If you\'ll look at the calcium plot on the other side, it shows similar
relationship with elevated calcium on Fortymile Wash, and lower calcium
on Crest, and also higher calcium at Oasis Valley.

So, this immediately began to suggest the compartmentalized nature of
flow in the Yucca Mountain area, and it wasn\'t just one sheet of water
soaring from one area to the other. It was consistent hydrochemistry.

This is further supported by carbonated plot on the left-hand side, and
even some of the minor constituents shows similar relationships, which
is the fluoride plot on the other side. You can see we had elevated
fluoride on the northern end of Yucca Mountain, and then slightly
decreasing fluoride as you get into the Fortymile Wash system.

So, this suggests to us this compartmentalized nature of the
hydrochemistry, and prompted us to divide the wells into a series of
hydrochemical facies.

And, rather than draw boundaries around these hydrochemical facies, and
many of you have seen these before, I\'ve chosen to just plot the wells
that we include within each facies in different colors so you can see
the western Yucca Mountain facies is represented by wells in this light
blue. Eastern Yucca Mountain facies is green, Fortymile Wash is yellow.
Bare Mountain, red. Amargosa River in blue, and the Eastern Amargosa
facies in black.

The constituents that are listed underneath of the facies title are
really the most significant constituents that we use to differentiate
these hydrochemical facies. The open circles down here below Highway 95
just indicate that the distinctions between the facies get a little more
fuzzy when you get down that far, due to mixing and the amount of
alluvium that it\'s passed through. So, we can\'t really be too
confident in some of the distinctions down there.

Binary plots are probably the simplest way to indicate some of the
distinctive nature of these facies. You can see the bicarbonate and
sodium binary plot separates walls from Fortymile Wash, the Fortymile
Wash facies, the eastern Yucca Mountain facies, the western Yucca
Mountain facies, Amargosa River facies and the Bare Mountain facies. It
doesn\'t do a very good job on the eastern Amargosa facies.

Sulfate and sodium does a little better job of separating the eastern
Amargosa facies. You have the same separation here, based on sodium. The
three facies that I\'m particularly going to talk about today, which are
the eastern, western, Yucca Mountain facies, and the Fortymile Wash
facies. And, these are just examples, binary plots of different
constituents, chloride and other ions will show similar relations,
depending on which facies you\'re looking at.

One distinguishing feature of the eastern Yucca Mountain facies is
elevated uranium 234 and 238 ratios. These elevated ratios have been
interpreted by Jim Paces as indicating limited local recharge through
the thick sequence of unsaturated rocks underlying Yucca Mountain. The
elevated uranium isotope ratios decrease to the south and within the
Fortymile Wash facies.

I\'d like to refer back to the infiltration map that was presented
several times in yesterday\'s presentations that Alan Flint made, that
indicated that the southeastern trending washes on the north end of
Yucca Mountain are estimated to provide 50 to 100 millimeters per year
of recharge under current climate conditions, and 100 to 500 millimeters
per year under the glacial transition period.

So, the hydrochemistry data here sort of indicates that most of the
water that enters the groundwater system in the Yucca Mountain area may
derive from those fault controlled washes on the north end of Yucca
Mountain. You can see from this borehole here, with the elevated uranium
234/238 ratio, that\'s Borehole G-2, it may be right in the area where
most of the recharge occurs, and then the water from the eastern Yucca
Mountain facies travels south, southeast towards the Fortymile Wash
system. It also seems to be somewhat isolated from water under the Yucca
Crest.

The relationship between these from the Yucca Mountain facies and
Fortymile Wash facies is demonstrated by these spider diagrams. Spider
diagrams are constructed by referencing the chemical constituents of
water well normalized to that of another well. So, if the wells contain
the same chemistry, then the plot would plot along this one to one ratio
line.

So, for this plot, I\'ve taken these wells in the central and southern
part of the Fortymile Wash closest, and normalized those to Boreholes
UE-25 A-1 and 2, which are also in the Fortymile Wash system, but are
north of Yucca Mountain. Those are the first two plots.

And, then, the third one is the same group of wells normalized to
Borehole C-3, which I\'ve taken as representative chemistry of the
eastern Yucca Mountain facies.

So, the first plot is referenced against Borehole A-1, which again is
north of Yucca Mountain in the Fortymile Wash facies. And, there\'s a
very shallow well, and it\'s influenced primarily by the alluvium. So,
you can see as the water flows down gradient from that borehole,
reference to that borehole, the primary changes that you see are
elevated fluoride concentrations. There is a little bit of unknown
differences, potassium in sulfate in one borehole, but overall, those
are plotting pretty much along the one to one ratio line, until you get
to the fluoride concentrations.

The second plot that is normalized to Borehole A-2, which is immediately
adjacent to A-1, but is influenced primarily by water from the volcanic
aquifer, shows the same increase in fluoride as you move down the flow
path, but it also shows increases in magnesium and potassium. This is
representative of the changes caused by moving from the volcanic aquifer
into a more alluvial aquifer, alluvial dominated aquifer to the south.

Then, the third plot normalized to Borehole C-3 from the eastern Yucca
Mountain facies shows a similar increase in magnesium and potassium,
since its water falling from the volcanic aquifer into a more alluvial
dominated aquifer in Fortymile Wash. But, the fluoride concentrations,
though, are similar between eastern Yucca Mountain and the lower part of
the Fortymile Wash facies.

So, to summarize, the mixing between waters in the two facies results in
only the fluoride concentrations in the Fortymile Wash facies before the
confluence, and elevated magnesium potassium result from the influence
of alluvium in the Fortymile Wash facies.

So, after looking at countless isopleth maps, binary plots, spider
diagrams, we finally came up with a map of major flow paths identified
from hydrochemical and isotopic parameters. These are not meant to
represent a particle track. These are supposed to represent large masses
of water, you know, myriad particle tracks together, flowing in a
similar direction.

So, we\'re not, you know, we\'re not really concerned about a particular
part of the track in this instance. But, the three primary flow paths
that we\'re concerned with now are the Fortymile Wash flow path, eastern
Yucca Mountain towards Fortymile Wash, and the southerly flow path from
Yucca Crest all the way down to Highway 95.

I dashed this line because we have a group of wells up here on the
crest, and we have another group of wells down here on Highway 95 with
similar chemical characteristics. But, there\'s quite a long distance in
between those two groups, and I think it might be a little bit of a
stretch to pretend that we\'re too confident that that\'s the same water
flowing down there.

So, those were attempts to put constraints or to verify some of the flow
paths generated by the modeling efforts. In an effort to constrain some
of the flow rates and travel times that are being generated by some of
the modeling efforts, we attempted to use carbon 14 dating as a tool.

Carbon 14 is a radioactive isotope, has a half-life of 5,730 years, and
it can be used to date groundwaters back to around 50,000 years.

There are some assumptions involved in dating with carbon 14. One is
that water acquires its initial carbon 14 content as it percolates
through the soil zone, enters the groundwater system.

In the absence of water/rock interaction, carbon 14 content would change
only as a function of radioactive decay, thus, allowing the direct
measurement of groundwater age.

Theoretically, carbon 14 measurements from wells situated along known
flow paths would allow calculations of travel time between each pair.

But, we live in the real world, and dating with carbon 14 in the
groundwater system has several problems. Particularly, carbon 14
measurements may give erroneous estimates of residence time if
assumptions are not strictly met. The acquisition of dead carbon from
aquifer rocks will result in determined carbon 14 ages that are
anomalously old.

Mixing of water from different sources, such as merging flow domains, or
recharge along flow paths, results in carbon 14 ages that are not the
true age of the water up gradient.

So, I\'ve put three plots of carbon 14 ages along flow paths, or
generally along flow paths anyway. They\'re represented by these sort of
trace lines that are on this base map over here. So, the first one is
from the same Boreholes A-1 and A-2 over here, down along the Fortymile
Wash system.

The second trace includes the eastern Yucca Mountain facies as it flows
towards Fortymile Wash, and then the third one are these wells that
represent the western Yucca Mountain facies.

You can see from the plot at the top, the carbon 14 age of Boreholes A-1
and A-2 are some of the youngest waters we\'ve measured in the whole
area. They\'re very shallow. There\'s a lot of recharge up there. And,
the ages are 3,000 to 4,000 years.

And, if you were to assume that all the carbon 14 assumptions were met,
you could calculate the distance between Borehole A-1 and A-2 and J-13,
and assume 10,000, or roughly 8,000 year travel time between those
points. The problem with that is that Borehole J-13 is located there, is
below the compliments of where we think that the waters from the Yucca
Mountain system merge with the waters from the Fortymile Wash system.

So, if you look at the ages of the waters from the eastern Yucca
Mountain system, they\'re approximately, what, 12 to 15,000 years. If
you mix those with the age of the water from Boreholes A-1 and A-2, you
come up with an estimated age of about 10,000 years, which clearly is
not true age of the water at that location.

If you go further down the system where the mixing is expected to have
already occurred, it\'s conceivable that we could use the age estimates
from these boreholes to make at least an estimate of travel time all
along the segment of the flow path. One of the problems with that,
though, is that Fortymile Wash is, most investigators think that
there\'s a certain amount of recharge along Fortymile Wash, so the
addition of recharge along Fortymile Wash would cause these estimated
ages to be younger than what they really are.

But, if you look at it in terms of those ages perhaps being minimums,
with your eyes open and realizing that there may be recharge added to
the system, you could take this distance and estimate a travel time
between these wells on the order of thousands of years, and just leave
it at that.

The eastern Yucca Mountain facies from what I\'ll call the headwaters up
on the northern end where these fault controlled washes exist, you can
see that the estimated ages are about 12,000, 13,000 years. There seems
to be a fairly steady progression away from that point to 15,000 years
at Borehole C-3. But, if you go further down the system, and I
apologize, we plotted this based on UTM Northern on the X axis, so these
wells are actually a little juxtaposed. WT-3 is actually west of J-13,
and it is the next well along this flow path.

If you go to WT-3, you\'ll see that the groundwater age is about 2,000
years younger than it is in the upper gradient well. WT-3 sits at a
fairly unique location. It is right near the intersection of where the
Bow Ridge Fault intersects with the water table, and it\'s expected that
there\'s a certain amount of recharge in that borehole. So, the cause of
this younger age is probably mixing of recharge.

But, if you wanted to, you could probably take the difference in age
between this short segment of the flow path and, again, make an estimate
that travel time is on the order of thousands of years.

In western Yucca Mountain, I\'ll go through this one very quickly, but I
gather you have a fairly good progression of the ages in these wells on
Yucca Crest, which you could estimate travel time of, again, thousands
of years between those points. But, if you tried to use the same
technique and include these wells down along Highway 95, first of all,
we\'re not sure of the flow path down there, and, secondly, the ages are
again younger, probably as a result of modern recharge.

To help us improve our estimates of travel time and groundwater age, we
have begun using dissolved organic carbon 14 ages to use in conjunction
with the inorganic carbon 14 to try and look for evidence of water/rock
interaction, and other things. While dissolved inorganic carbon 14
activities are altered by water/rock interaction, the dissolved organic
carbon 14 should remain unaffected.

Dissolved organic carbon 14 measurements are still affected by mixing,
by the introduction of recharge, and the presence of organic
contaminants.

These are very preliminary results, and I think some of the members of
the Board have seen this before. Unfortunately, we haven\'t been able to
increase the size of this data base, but this is a plot of percent
modern carbon from the inorganic carbon 14 on the Y axis, and dissolved
organic carbon 14 on the X axis.

If these were plotting and giving us the same age, they were all plotted
along this concordant line. And, you can see it for the wells in Yucca
Mountain, they are mostly from the volcanic aquifer. It looks like
there\'s very little correction that\'s going to be required to convert
the inorganic carbon 14s into a true age.

But, when we get into the wells from the Nye County Drilling Program,
which are these wells down here in green, and a group of wells in the
Amargosa Farms area, you can see that they\'re quite variable, and there
will be some considerable correction having to be made. Most of the
organic carbon 14 ages are considerably younger than those predicted
from the inorganic carbon 14.

So, conclusions are that the saturated zone waters near Yucca Mountain
can be divided into six distinct hydrochemical facies that maintain
their chemical and isotopic character over long distances.

The hydrochemical facies can be used to identify general flow domains
and mixing relations between facies.

Water from the eastern Yucca Mountain facies may obtain its unique
isotopic signature due to recharge through the fault controlled washes
on the northern end of Yucca Mountain. This water then flows
south/southeast until it eventually merges with the Fortymile Wash
system.

Water from western Yucca Mountain facies flows south, at least as far as
the southern tip of the mountain, and perhaps as far as Highway 95.

Although estimates of travel time over long distances based on carbon 14
ages are difficult, travel times within part of Fortymile Wash and part
of the western Yucca Mountain facies appear to be on the order of
thousands of years rather than tens of years.

Thank you. Well, I guess I do have one more slide. I\'m sorry.

One of the questions the Board asked was what can we do in the next
several years to increase our understanding of the system. We have
several programs that are ongoing now that I think will help. Continued
measurements of unsaturated zone pore-water chemistry in the deepest
part of the unsaturated zone will help assess the nature of the UZ/SZ
interface and refine our interpretations of flow paths away from the
repository.

Continued refinement of the methods used to sample and analyze dissolved
organic carbon 14, along with dissolved inorganic carbon 14,
measurements and reaction path modeling will provide better estimates of
transport along certain flow paths, which is work that we\'re doing
under the Science and Technology Program.

And, then, continued investigation of three dimensional flow and the
interface between the volcanic aquifer and the alluvium south of Yucca
Mountain will help refine the interpretation of flow paths, and we\'re
doing this as part of the Nye County program.

That\'s it.

BULLEN: Thank you, Gary.

In my introduction, I was remiss in not giving a little bit of
background on you, so I\'ve got to make up for that now, particularly
since you graduated from the University of Illinois, where I now live.

After that graduation, you spent some time on the Sheffield side in
Wisconsin for the USGS, and have been, for a very short time with the
Yucca Mountain Project, since 1989.

PATTERSON: Yes.

BULLEN: And has been in planning the design of the C-wells complex,
multi-well pumping test, and been a principal investigator on the
pneumatic pathway and gas phase circulation in the ESF. So, I wanted to
get that on the record before we asked if there were questions from the
Board with respect to your presentation. We\'ll go to Thure Cerling,
Priscilla, and Richard.

CERLING: Cerling, Board.

I was just wondering how your carbon 14 data in these water measurements
can be interpreted in the light of how long things take to travel
through the unsaturated zone. Is it compatible? And, part of that
question, a follow-up question would be have you analyzed carbon 14
content of sort of deep soil gas in the unsaturated zone?

PATTERSON: We have analyzed carbon 14 in the deep gas phase. I\'m trying
to remember, it was a number of years ago, in the deep UZ, I think the
carbon 14 ages that we came up with were on the order of, oh, 7,000 to
15,000 years, and I guess if we assume that the water picks up its
carbon 14 as it passes through the soil zone, then we have to assume
that the travel time in the unsaturated zone is sort of rolled up into
part of this. But, there is a lot of gas phase exchange between matrix
in the unsaturated zone, and water that\'s in the unsaturated zone, and
in general, so that the actual carbon 14 age that reaches the saturated
zone is possibly significantly altered by the time it reaches the
saturated zone. Good enough? You look doubtful.

CERLING: No, no, I just understand it, I just wondered if you\'d sort of
tried to model the carbon 14 information with respect to transit in the
unsaturated zone, and then once you\'re in the saturated zone, you\'re
starting at some initial conditions. And, it kind of cuts to the
question of well, when hits the unsaturated zone, what\'s the sort of
zero age?

PATTERSON: I think Al Yang did a lot of calculations on gas phase carbon
14, and actually I did quite a few of them myself, but I was primarily
involved in the ESF, and, so, they never really got linked from the
surface down. And, the ESF, of course, is well above the saturated zone,
so I\'m not sure I could really give you a number. But, there have been
efforts to do that.

CERLING: And, then sort of a related follow-on question, just for all of
the data that you\'ve presented, you didn\'t say in the very beginning
over what sort of hydrologic interval that might represent. I mean, I
presume it\'s all pretty much the same, but I wasn\'t sure.

PATTERSON: Three dimensions?

CERLING: Sure.

PATTERSON: Okay. Most of our data base is the upper few hundred meters
of the saturated zone. The bottom investigation that you see there is to
look at more detail in the three dimensional flow. We\'re embarking on
an effort to use a model, it\'s called M-3, it was developed in Sweden,
and it\'s a combination principal component analysis and kreeging model
that will interpolate data between the various points that we have. We
don\'t have a lot of control at depth in some of these areas. Nye County
effort in the alluvium is adding to that quickly, and we now feel like
there\'s enough data that we can pursue that effort.

CERLING: Well, then, in one of your earlier diagrams where you showed
the sodium and the calcium and other plumes, I was just wondering how
different the aquifer matrix was between different areas in that plume.
Is it essentially the same?

PATTERSON: Well, there are differences. The Fortymile Wash facies flows
primarily in an alluvial dominated system. The Yucca Mountain facies are
both in volcanic rocks. As you move south of Highway 95, you\'re back
into alluvium. Bare Mountain is greatly affected by Paleozoic
carbonates. The Amargosa River facies is affected by Pre Cambrian
quartzites. So, there are a variety of different aquifer materials in
the area.

CERLING: Thank you.

BULLEN: Priscilla Nelson?

NELSON: Nelson, Board.

I\'ve got two questions. One is over this time framework extending to
20,000 years, is anticipated past climate changes enough to affect
interpretations of mixing or flow paths? Is that a possibility?

PATTERSON: Well, it\'s a possibility, but I think most of the models
that we\'ve seen over the last day and a half don\'t seem to indicate
that flow paths have changed very much in the climate conditions. You
can get more infiltration. We are probably looking at waters now that
came from the events 10,000 years ago, or so. I don\'t think that, first
of all, I don\'t think we have enough information to really assess that.
Yes, I think it\'s possible that it could affect them, but the evidence
that we\'ve been given in the last couple of days, if you believe the
models, the flow paths at least have not changed a lot.

One effect, if I may, is that as the water table rises, we may get
changes in flow across faults that are now being considered as barriers.

NELSON: Right, it is complicated. Just following up on that, I was
struck by the Center\'s models that showed, because it\'s a relatively
low gradient for the flow underneath the repository, so the influence of
change in precipitation right over the mountain can be significant in
terms of causing flow. So, it seemed that that might be another factor
that further complicates this.

PATTERSON: Yes, I think it would be. And, you\'re right, it\'s a very
flat gradient.

NELSON: You want to go after the interpretation, but it\'s hard in this
case, isn\'t it? Let me ask you one other thing. Have you done similar
kinds of work that encompass the perched water zones?

PATTERSON: We have chemical analysis from the perched waters.

NELSON: Any carbon 14 analyses?

PATTERSON: Carbon 14 in the perched waters is somewhere in the 10,000 to
12,000 age range, fairly similar to that of Yucca Mountain, where we
have good samples. Some of the problems in some of the perched water
bodies, we haven\'t really been able to get what we consider a high
quality sample, and, so, some of the ages look a little weird from that,
and we don\'t like to really talk about them.

NELSON: Do you think that they would be informative? Could you get a
good sample in trying to help figure out this question that Thure was
raising about UZ?

PATTERSON: Some of the identified perched water bodies have started at
the bottom in some of the UZ boreholes, and things like that, where we
were able to use a bailer to pull up water, which was primarily mud, and
probably fairly affected by the drilling. Those water bodies that are
large enough that we could pump and collect a good sample from, we have
already.

NELSON: Those would be interesting. Thank you.

BULLEN: Richard Parizek?

PARIZEK: Parizek, Board.

Thank you again for a good integration of your data sets. One question
on the last bullet on what you plan to do, or ongoing activities. Will
that allow some additional drilling dedicated drilling for this purpose?
Because obviously all Nye holes or any new holes help, but the idea of
multiple completions, the old West Bay idea, hasn\'t been carried on
recently, I guess for funding reasons. And, so, the quality of
information you would like to have isn\'t always available. You\'ve had
to kind of make do with often pretty mixed up samples with holes at
variable depths, and different units, and sort of a (inaudible) data
base. Do you include dedicated drilling for these refinements?

PATTERSON: The only drilling that\'s included in any of these studies is
that that\'s conducted by Nye County.

PARIZEK: So, you piggy back onto that process.

PATTERSON: Right.

PARIZEK: Do you have a chance to weigh in, I hope, in terms of what
you\'d like to see on these deliberate pathways to finally, because you
have a validation opportunity which can be value added to the program,
providing you could feel comfortable with the location of wells, and
where they\'re completed, and the flow channels as identified; right?

PATTERSON: Yes. I think we can at least discuss things with Nye County,
and their new sonic drilling program may allow us to extract pore water
from the consolidated cores and get depth discretized samples. And, if
that program continues, and if it gets funded, I know they\'re
interested in doing a lot more of that. And, if they do, then that\'s
how we expect we might be able to expand that 3-D data base.

PARIZEK: Parizek, Board again.

Since you\'ve been out in the program so long, you were a member of the
TSPA/VA days, when the plume was wide and deep and quite dispersed, and
then it got narrow, and it\'s sort of what\'s captured in presentations
this morning. So, it\'s narrow, and I can\'t help but look at your
figures on Page 3 and 4, and your chemistry smears along the Fortymile
Wash area. Now, again, you could argue maybe there\'s infiltration
occurring through time at different places, and it sort of broadens that
whole thing out. But, what do you think? Do you think the narrow, not
quite pencil line thin, present model runs are supported by your
chemistry, whether you use the sodium, the calcium, or others? Can you
help us with that?

PATTERSON: Do you know which page that is?

PARIZEK: What you\'ve got is 3 and 4 of yours.

PATTERSON: I think the flow maps are probably around 6 or 7.

PARIZEK: The arrows are 10.

PATTERSON: The arrows are on 10? Well, the narrow flow paths along
Fortymile Wash, I think are, in one way, they\'re a function
of\--they\'re model generated. And, if you assume each recharge along
Fortymile Wash, then you have to assume that there\'s a hydraulic mound,
no matter how small it is, there has to be a mound under Fortymile Wash.
So, the model will now allow flow to go past that mound, or to go up
gradient along that mound. So, I think it tends to take the flow from
the west and just sort of slam it up against that hydraulic mound and
then immediately drive it to the south.

I think what we envision, again, is these myriad flow paths coming
across. And, I\'ve got this drawn so that it sort of bumps into
Fortymile Wash, and I think the spider diagrams indicated that there\'s
mixing between those two, and I also think that there are wells, if we
have the facies map up there, you\'ll see wells of eastern Yucca
Mountain facies waters that are all the way down here. So, it doesn\'t
all slam in a mix with Fortymile Wash. So, I think some of it does come
in here and mix, and I think some of it does flow in this more southerly
direction, and persist all the way down into this area here.

So, you know, whether that\'s a narrow flow path or not, I don\'t know.
Again, it\'s a function of flow paths, and there are a bunch of particle
tracks anyway, and, so, the relationship from the mixing at the margins
of these facies is something that we don\'t have real good control of.
And, so, I guess I\'d have to say that I can\'t really argue with their
representation of flow as this being probably the most important flow
path that we\'re talking about right now in terms of a repository. And,
I think if you\'re going to model it, I think that\'s probably the way
you have to do it.

PARIZEK: Parizek, Board, again.

It\'s a idea of whether or not that mound would exist maybe during
periods of intense runoff, episodic recharge, that might be there for a
while, and then dissipate and reappear. So, that again, could create a
lateral smearing basically of a plume, which is beneficial to diluting
the plume. So, the details of that might be worth investigating if you
really think it\'s a pen line right up against those two bodies of
water. But, it may not be that. It may be spread out more.

PATTERSON: There\'s no reason to believe that that has been in the same
place over long periods of time either. But, again, how we would go
about investigating something like that, I don\'t really know.

PARIZEK: There was another opportunity, we\'ve asked about, some years
back, about whether you have any unique waters that, say, come out of
like Crater Flat, that comes along with distinct signature, and then it
mixes, and, so, which you can then begin to get some sort of
dispersivity numbers from, long-term experiments. And, this was raised
before. I guess there was no clear-cut places you could do that very
well; right?

PATTERSON: I think the most unique feature that we found so far is Jim
Paces finding of 234, 238 ratios, that seems to be a tracer of sorts. As
a matter of fact, I think if we had a lot of three dimensional control
and different, you know, additional boreholes, that could be used almost
as a tracer.

PARIZEK: \--dispersivity number, which the program really doesn\'t have
right now. So, would there be value added if you could do that?

PATTERSON: Well, sure.

PARIZEK: It\'s just a question of whether you could do it?

PATTERSON: It would take additional boreholes, and it would take, you
know, a fair effort. You know, we live in the real world, drilling a
borehole out there is pretty expensive. So, I don\'t think it is really
my place to stand here and say we need a hundred boreholes.

PARIZEK: But, if we take John Bredehoeft\'s recommendation, leaving it
open for a thousand years, think of the manpower that it takes to guard
that place. So, in a way, if a regional dispersivity number is useful,
it\'s possible maybe to squeeze one out of this, out of years of work,
and now you\'re at a point where if you could drill, you could probably
optimize\--

PATTERSON: I think that\'s true.

BULLEN: Bullen, Board. We\'re going to have to move along, Richard. And,
Frank, we\'re going to ask you to delay your question until we have the
roundtable\--or the open forum discussion a little bit later, and maybe
we can get a comment or two. Oh, he\'s not going to be available.
That\'s right.

Okay, so Frank\'s is the last question. Or question? Two questions, but
they have to be less than two minutes long.

SCHWARTZ: The questions will be short. It\'s the answers that will be
long.

Gary, I had one question here with regard to the slugginess of the flow
paths from the geochemical indication seem to be much slower than sort
of the model calculations would suggest. I mean, is that your feeling as
well?

PATTERSON: Yes. I think they are. I mean, I think because of the way the
models have to use extremely conservative values for all of their
parameters, they\'re going to be realizations that make the water just
fly. But, I don\'t think we see, in the places where we can actually
feel reasonably confident in our estimates, the travel time seems to be
longer.

SCHWARTZ: The last question I have is with respect to where might there
be young water? I mean, I guess I\'m impressed by all the dating and
even the corrected dating seems to rarely find young water. I mean,
Number 1 and 2 in the north there seem to be young. But, even under
Yucca Mountain, if you assume fast flow paths exist, for example, you
would expect to find some young water there, and I guess it\'s my
impression that there is no young water to be found from a geochemical
perspective. Am I wrong there?

PATTERSON: Well, if you consider the amounts of recharge that we\'re
talking about here, with infiltration rates of, you know, 50 millimeters
a year, or whatever, and this huge reservoir of water that\'s already in
the saturated zone that\'s a mixture of waters from older and younger, I
don\'t think you would see real young water. I think A-1 and A-2 are the
closest thing that we\'ve got to young water. If you, you know, dropped
an ounce of water in a bathtub, an ounce of water with one
characteristic in a bathtub, you probably wouldn\'t see it when you made
the measurement.

SCHWARTZ: But, I guess to me, it kind of implies that this idea of these
fast flow paths perhaps is not delivering very much water.

PATTERSON: No, and I don\'t think anyone\--

SCHWARTZ: I guess that\'s where I was kind of going.

PATTERSON: I think the talks that you heard yesterday were the same,
fast flow paths exist, don\'t exist, you know, there\'s a small amount
of water and they don\'t really matter.

SCHWARTZ: Thank you.

BULLEN: Thank you, Gary. Moving right along, we have our next
presentation by Stephanie Kuzio, who is the manager for saturated zone
department for BSC, from Sandia National Laboratories. She has her civil
engineering degrees, undergraduate and graduate from the University of
Maryland, and she basically is a saturated zone manager for Yucca
Mountain Project. She manage and coordinates the saturated zone
technical activities related to the products for license application.
And, she will be speaking about sorption, matrix diffusion, and
colloid-facilitated transport in saturated zone radionuclide transport
models. Stephanie?

KUZIO: I\'m figuring out the technical difficulties here. My
presentation today, will cover the three key transport processes that
are included in the saturated zone transport modeling, and that\'s
sorption, matrix diffusion, and colloid-facilitated transport.

I\'d like to recognize the PIs on this work, and they are Sharad Kelkar,
Paul Reimus, Arend Meijer, Hari Viswanathan, Rajesh Pawar and Mei Ding
from Los Alamos National Laboratory, and from Sandia National Labs, Bill
Arnold.

A brief outline of what I\'ll be discussing today. For each key
transport process, sorption, matrix diffusion and colloid-facilitated
transport, I\'ll discuss the conceptual model or approach, and then
we\'ll look at the barrier capability of each one of these transport
processes, and then I\'ll conclude.

So, at a very high level, matrix diffusion of dissolved radionuclides is
implemented in saturated zone transport modeling in fractured volcanic
units.

Particle tracking with the FEHM code is used to simulate the
radionuclide mass migration in the saturated zone. The valley fill
alluvium is simulated as a porous medium, using the effective porosity
approach.

A linear sorption approach is used in the matrix of the volcanic and
alluvium units. And, colloid-facilitated transport of radionuclides is
simulated to occur by two modes, an irreversible mode and a reversible
mode. And, I\'ll talk about those in further detail as we go through the
talk.

This is a satellite image of Yucca Mountain. The yellow outline
represents the repository. The model boundary is shown in this red
border around, which is 30 by 45 kilometers. That\'s the site scale flow
and transport model domain boundary. The blue line is Highway 95. The
red crosses are well locations. Fortymile Wash comes down, shows up very
nicely here on this plot. Crater Flats over in this area.

This is our hydrologic framework model, which the flow and transport
model is based upon, Claudia discussed this morning. We have an
orthogonal grid, and we have 500 meter spacing. There\'s variable
resolution in the Y direction, or Z direction, and that is more finely
discretized around the repository area, which is about up in here. The
units that are most important to transport are the Crater Flat group,
which consists of the Prow Pass, the Bullfrog and the Tram hydrogeologic
units. Because the flow is within the first few meters, as some other
speakers have pointed out, those are the units that are impacted the
most. And, this cross-section down in the corner also reflects that.
This is a cross-section up near the repository area. You can see a lot
of these colors that are associated with these units.

You\'ve seen this figure before. This points out the various different
transport processes that we have in the saturated zone transport model.
This is a north/south cross-section through the Yucca Mountain area. The
proposed repository is shown here in black. The radionuclides will
migrate down through the UZ, with the breaching of the waste packages.
They will reach the water table, and enter into the volcanic aquifer,
which we, our conceptual model is that this is a fractured medium.

The radionuclides then will continue to travel through this volcanic
aquifer until it reaches the alluvium aquifer. This is an uncertain area
where this contact actually is, and it\'s treated that way in our
transport modeling.

Within our fractured medium, we have advection within the fractures,
flow is within the fractures, and we have matrix diffusion occurring
into the matrix block. Within the matrix block, we have sorption,
sorption occurs within the matrix block.

This figure shows our schematic diagram of our matrix diffusion submodel
geometry and assumptions. Our approach utilizes a dual porosity model
with equally spaced, parallel fractures, as shown in this figure. The
effectiveness of matrix diffusion is dependent upon various different
things. The properties of the matric itself, and also the spacing of
these flowing intervals, the zones that actually transmit groundwater
flow. The closer those are together, the more matrix diffusion that can
occur. The farther those are apart, the less amount, the less diffusion
that will be able to occur.

This approach is fairly well based on results from the C-wells reactive
tracer test, and that leads to my next slide.

These are results from the C-well reactive tracer test. The C-well
reactive tracer tests occur, were done in the fractured volcanics, and
pumping from well to well at a distance of approximately 30 meters.

The first thing to notice in looking at these figures is that we have
two peaks, or two humps that occur in all of these results, and that\'s
what\'s interpreted as that there was two advective pathways that
resulted in those two humps.

The second important thing, looking at the PFBA and the bromide results,
well, first looking at the scale, and this is a normalized concentration
on a log scale on the Y axis, and it\'s logged as well on the X axis,
and there\'s slight differences visually here, but this is a log scale.
There\'s a difference between the PFBA and the bromide reactive tracer
results, and the primary reason for that is the difference in the
diffusion coefficients between the bromide and the PFBA.

The lithium, the peak is at the same time, but it\'s at a lower
concentration, indicating that sorption is present as well as matrix
diffusion. At later times, the lithium second peak actually occurs at a
later time, which is what one might expect with absorption and matrix
diffusion occurring at the same time.

The very last curve is microsphere results from the reactive C-well
test, and they show a very similar fit. Microspheres are delayed. They
break through a little quicker. Their peak concentration here is a
little bit quicker than the others, but there is some attenuation that
does occur there.

So, the important thing to note about this is these were modeled
successfully including a dual porosity matrix diffusion approach. What
is not on this figure is the last bullet, the preliminary, we have some
single well tracer test results, which confirms a porous medium
behavior.

This is to look at the saturated zone barrier capability for matrix
diffusion. How much does matrix diffusion contribute to the delay of
radionuclides through the system.

The solid black curve, which is right next to the dashed red one here,
is our base case simulation, which includes a diffusion coefficient, but
it includes no sorption. So, in comparing this diffusion case, the is a
median value for a diffusion coefficient, and comparing that to a no
diffusion case, which is the light blue dashed line, you can see that
there is some benefit, some delay in spreading of the curve as a result
of including matrix diffusion.

Now, to talk about sorption within the saturated zone and how that\'s
implemented. We expect certain radionuclides to have sorption
capabilities. There are some radionuclides that we\'ve shown through
testing that don\'t sorb, for example, technetium and iodine, and they
have transported through the system without any sorption.

For radionuclides that do sorb, examples of that would be neptunium,
uranium, we have a linear sorption approach that\'s used in the matrix
of the volcanic and the alluvium hydrogeologic units.

We assume no sorption on fracture surfaces. The sorption that occurs,
occurs within the matrix. We also assume geochemical conditions along
the entire flow path length. The geochemical conditions assumed are
oxidizing, as opposed to a reducing condition. If we had a reducing
condition that we assumed, our Kd\'s would be higher, which would result
in greater transport times.

There\'s many factors that influence sorption coefficients, so in order
to capture the uncertainty for sorption coefficients, we\'ve done that
through probability distributions. We use a single value for a sorption
coefficient for any one particular realization. We do, though,
distinguish between the volcanics and the alluvium units.

The probability distributions for sorption coefficients include
variations in water chemistry, in rock surface properties, and
mineralogical compositions. The probability distributions are based on
experimental data that we have available, and, then, professional
judgment has been used regarding the impact of variables not considered
in experimental program. There are some recent alluvium experiments that
were conducted for neptunium, uranium, and the results from that, the
Kd\'s, are corroborating the distributions that we currently have for
neptunium and uranium.

There was also a study done to compare variability of sorption
coefficients at the scale of the model grid blocks to variability at the
lab scale. And, what we found was that the variability at the lab scale
is less than the variability at the\--the variability at the grid block
is less than the variability at the lab scale. So, that was incorporated
when we put together these probability distributions.

So, to look then at the barrier capability for sorption, the first
curve, this is our same curve that we saw previously, this solid black
line, the non-sorbing medium diffusing base case curve, and we\'re
comparing that to three other curves that include sorption. The first
curve is this little dashed red line, and that includes just matrix
sorption. So, you can see we do\--there is some increase in transport
times there as a result of that.

When we look at just alluvium, there\'s a significant increase when we
look at alluvium sorption added onto the models, this light blue dashed
line. And, then, when we look at the combination of matrix and alluvium
sorption, we\'re looking at on the order of I think it\'s approximately
two orders of magnitude that we\'re able to accomplish. And, the Kd\'s
that I used for that are listed here. Neptunium is a fairly moderately
sorbing radionuclide. So, even for a moderately sorbing radionuclide, we
show some significance, and times and spreading of the distribution.

Now, to talk about saturated zone colloidal transport, in the saturated
zone at Yucca Mountain, we were aware that there are naturally occurring
colloids. And, with the breaching of the waste packages, the degradation
of the waste packages, we\'ll be adding, the system will be adding, the
waste packages will be adding additional colloids to the system.

One of the first types of colloids which is shown, this figure is a
conceptualization of these two modes of transport that are implemented
in our model to represent colloidal transport, and the first type is
this theory on this very bottom figure which is shown, this is to
represent fractures, and this is our matrix here, and these are the
irreversible type which they\'re created from the high level waste glass
products as they degrade. And, here, the radionuclide is part of the
structure. It will not, these types of colloids, the radionuclide is
embedded in the structure and will not come off. And, I\'ll talk about
the details of how that\'s implemented in our model in the next couple
of slides.

Then, the other kind of colloid is this large brown ball here that you
can see in the fractures, and that\'s our reversible type colloid. And,
that type of colloid, we can have attachment and detachment of
radionuclides onto it as it travels through the system.

Something to notice in this figure is that these colloids stay within
the fractures. They don\'t diffuse into the matrix at all.

So, we have two types of colloidal transport, a reversible attachment to
colloids and an irreversible attachment.

For irreversibly attached colloids, they are in equilibrium with the
aqueous phase and the aquifer material. In this mode of transport, the
effective retardation of these radionuclides during transport is
dependent on three primary things. How strongly the radionuclide will
sorb onto the colloid, the concentration of groundwater colloids
available for those radionuclides to sorb onto, and then the sorption
coefficient of the radionuclide onto the aquifer material as it moves
through the system.

For irreversible colloids, radionuclides that are attached irreversibly
are transported at the same rate as the colloid. Colloids with
irreversibly attached radionuclides are themselves delayed by
interaction with the aquifer material.

The implementation of that is we have a retardation factor that\'s
applied in the volcanic units for irreversible colloids, as well as a
separate retardation factor that\'s applied in the alluvium.

For these types of colloids, irreversible type, there is a very small
fraction that is transported through the system unretarded, very
quickly, as was mentioned yesterday in the UZ talks, and this phenomenon
has been observed at the NTS site, a couple different field observations
has confirmed this. So, we\'ve included this in the modeling.

This slide describes the implementation of the different radionuclides
that are transported colloidally through the system. Plutonium and
americium can be transported in two ways, either irreversibly or as a
reversible colloid. That\'s why you see them in both sections there. So,
plutonium and americium are two radionuclides that are transported
irreversibly, and then plutonium, americium, thorium, protactinium and
cesium are treated reversibly, and they\'re done in this manner down
here in these three bullets.

Cesium and plutonium are transported separately, and then americium,
thorium, and protactinium are transported in one group, the Kd\'s on, so
the colloid are very similar, so we\'ve grouped them together.

Again, this is our same, this is the barrier capability for colloids,
and this is our same base case curve again, which we\'re comparing to a
median value for irreversible retardation in the volcanics and the
alluvium. And, here, the barrier capability is approximately an order of
magnitude, with inclusion of irreversible colloids.

So, to summarize, the key transport processes included in the saturated
zone transport model are matrix diffusion, sorption and
colloid-facilitated transport.

Matrix diffusion delays transport times and spreads the arrival times of
radionuclides. Sorption in the alluvium can increase the transport times
by orders of magnitude for even weakly sorbing radionuclides such as
neptunium, the example we looked at. And colloids irreversibly and
reversibly bound to radionuclides may be delayed by several thousand
years.

That\'s it.

BULLEN: Thank you, Stephanie. I\'ll start with questions from the Board.
Dr. Nelson first?

NELSON: I\'m always the first one. Have you noticed that.

I want to ask just a general question. At some point in the past, this
is Nelson, Board, we had a lot of discussion about whether the water,
the saturated zone water, was reducing or oxidizing. So, I\'m wondering
what the current thinking is of that, and whether that has any impact on
transport.

KUZIO: Right. I meant to talk about that a little bit as I went through.
We\'ve assumed the oxidizing conditions. We do have some results from
testing at different wells that does indicating reducing conditions, but
it\'s not consistently shown everywhere, and we have a limited data set.

NELSON: Okay. So, you\'re assuming oxidizing because it\'s conservative?

KUZIO: Correct.

NELSON: But, it might be reducing?

KUZIO: In some areas, it\'s shown that it is reducing. The full story
isn\'t in yet.

NELSON: Okay. Let me ask about one other thing. The accent on matrix and
flow through rock mass, fractured rock mass, what if the flow is really
in a fault zone through the rock mass, what part of your story would be
different, how well do you have the fault material characteristics
characterized? Has that been the subject of thinking?

KUZIO: Well, I would say that\'s more in the flow area, and that the
faults have been represented in the flow model, either as people have
pointed out here previously, some of those faults are barriers to flow,
and some of those faults are conduits for flow.

NELSON: Nelson, Board.

So, if one is a conduit, and it\'s taking quite a bit of flow, the
character of the transport might be quite different than if it were
through the rock mass; is that true?

KUZIO: Right. And, you\'ve seen the results that Ken Rehfeldt presented
earlier that show\--I mean, we\'ve got a tremendous uncertainty in our
parameters. We\'ve got some very early breakthrough times that may be
representative of that sort of thing. Bill Arnold will probably talk
about this to some degree.

NELSON: Oh, we\'re going to have to talk to Bill for a long time.

KUZIO: Yes, I know, long awaited discussion with Bill.

NELSON: We\'ve been deferring a lot of things to Bill.

KUZIO: Bill is our point man.

NELSON: Okay, then I yield to Bill.

KUZIO: Okay.

BULLEN: Rien van Genuchten.

VAN GENUCHTEN: Yeah, I have two different things I want to raise here.
One is on your Page 8, or Slide 8, when you talk about matrix diffusion.
We all agree about the conceptional picture. I\'m curious how this was
implemented in your model, if you use actually diffusion integrations,
or you use a first order exchange, or how did you do this?

KUZIO: Well, Bill will talk about this probably in a little more detail.
There is a particle tracking that is implemented that utilizes the
Sevougian equation. Does that help at all? That\'s how the diffusion
moves along into the matrix and diffuses back.

VAN GENUCHTEN: So, how does the matrix eat away from the concentration
and the fractures? How is that implemented?

KUZIO: Eat away from the fractures?

VAN GENUCHTEN: Well, the diffusion loss.

KUZIO: I\'m not sure I understand. The motion, how that\'s included?
I\'m sorry.

VAN GENUCHTEN: The mechanics of how does this being modeled, I\'m
curious about. You say this is done with particle tracking. So, you have
actually particles moving into the matrix?

KUZIO: Well, simulated\--I\'m probably not the best person to answer
that. But, yeah, the particles move along through each grid cell, and
depending on, there\'s a library of breakthrough curves that are used
based on the Sevougian equation that moves the particles along, also the
concentration, it randomly moves them into the matrix and out again. The
dual porosity model, I\'m not giving it what you\'re looking for.

VAN GENUCHTEN: Okay. Then I have a few questions about the colloids. I
was a bit confused. First of all, you have, you say, reversible
colloids, attachment and detachment. Is that considered to be
filtration, or absorption?

KUZIO: You\'re referring to reversible?

VAN GENUCHTEN: The reversible.

KUZIO: They attach to\--they attach and detach from the colloid
themselves. What was the second part?

VAN GENUCHTEN: Yes, is this done in a kinetic way so there will be a
forward and a backward rate degradation?

KUZIO: That isn\'t how it\'s implemented in the model, no, we don\'t
include kinetics in that model, no. It\'s an effective retardation,
basically, is how it\'s implemented.

VAN GENUCHTEN: So, that\'s on your Slide 15, you stated it, so you use
an equilibrium process for that.

KUZIO: Correct.

VAN GENUCHTEN: That\'s right. And, then, for the irreversible ones, are
you using a sink drum, like a first order rate degradation for that?

KUZIO: Again, there\'s retardation factors that they looked at, those
retardation factors were based on looking at attachment and detachment
rates, but they came up with retardation factors that we could then
apply essentially as an effective Kd through the system. So, it\'s not
explicitly included. And, we don\'t filter colloids. We don\'t lose any
physically. I didn\'t make a point of that either.

VAN GENUCHTEN: Okay, thanks.

BULLEN: Frank Schwartz, and then Richard Parizek. Frank gets to talk
before you, Richard.

SCHWARTZ: Thank you, Schwartz.

The question I had for you, maybe if you go back to Slide Number 8, the
direction there, 2B, the distance between the fractures, is that a large
number to reflect this idea of flowing intervals, such that that number
would be 10 or 20 meters, say?

KUZIO: The distance between the zones that we consider flowing is 20
meters. And, that\'s our\--

SCHWARTZ: Yes, that\'s okay. And, that\'s the way the model is set up?

KUZIO: Yes.

SCHWARTZ: The question I had for you was that I wonder if there\'s
correlation among the variables that you\'re using. For example, when
you create a head field and you need a velocity out of that head field,
you need an effective porosity number, I\'m wondering do you select the
effective porosity randomly, and then select block size randomly as
well, or is there correlation among that pair of variables?

KUZIO: Effective porosity in the alluvium?

SCHWARTZ: Well, effective porosity in the fractured rock.

KUZIO: In the fractures. Those are separate samples independently.

SCHWARTZ: Okay.

KUZIO: They\'re not correlated.

SCHWARTZ: Because you could run into a situation where if you chose a
big effective porosity, you know, a fairly small effective porosity
could imply big 2B, and yet I guess, you know, if the effective porosity
was, say, .01, that would imply 2B was a lot smaller, because there
would be a lot more fractures.

KUZIO: Right.

SCHWARTZ: So, that was always an issue that was one of my sort of pet
peeves along the way, was the sort of lack of correlation among the
obvious verticles. I just wondered whether you\'ve been handling it.

KUZIO: We\'re still sampling those independently.

SCHWARTZ: Okay. I think that\'s it for me. Thanks.

BULLEN: Richard Parizek, and then David Diodato gets the last question.

PARIZEK: Parizek, Board.

Sonic drilling methods were used in perched factor core recently by Nye
County, and some of the classes that came up were highly decomposed,
chemically altered, would not have been preserved in rotary methods of
drilling. But, obviously, they have a matrix diffusion possibility. The
program I guess did not take any credit for matrix diffusion in the
alluvium, is that correct?

KUZIO: That\'s correct.

PARIZEK: Even though it looks like you could get credit for it based on
what we see from the samples that came out of that core.

KUZIO: Well, there was one bullet where I did talk about some testing
that was done at the ATC. These are preliminary and fairly new, where
they did not see matrix diffusion in the alluvium. That was my goal,
continuum most appropriately.

PARIZEK: Okay. Parizek, Board.

For some of the variables that were not included in testing, you did use
external peer review process in the past, technical basis document
refers to this. I was wondering whether or not the program intends to do
that again with regard to the newer data that may have come out of the
alluvium testing, you know, some of the single wells, some cross-well
testing.

KUZIO: In terms of our expert panel?

PARIZEK: Right, trying to get anymore data out of what exists here to
help constrain your models. Do you know if that\'s planned?

KUZIO: Planned to have an expert elicitation?

PARIZEK: No, like reviewing the data base, basically, with external
opinion.

KUZIO: At this time, that isn\'t planned.

BULLEN: David Diodato.

DIODATO: Diodato, Staff. Thanks for this presentation.

You know, in your talk, and in other talks, and then sneaking ahead and
looking forward at Bill Arnold\'s talk, it seems clear that the program
has an idea that matrix diffusion might in fact be fairly significant
and an important process in terms of radionuclide transport. And, you
have this flow and interval spacing, and I guess there\'s some field
measurements that go with that? There\'s some field tests and
observations you\'ve made to determine this flow and interval spacing;
is that correct?

KUZIO: Yes. Flow meter surveys were primarily used. We have a limited
data set on that, but we looked at USGS borehole reports, flow meter
surveys, and basically did a statistical analysis looking at the spacing
between the zones that were flowing.

DIODATO: Thanks. Diodato, Staff.

Just to follow up on that then, how many measurements do you have of
flow and interval spacing?

KUZIO: If my memory serves me, it was a while ago, it was about 27 data
points that were used to determine the distribution for the flow and
intervals. But, we\'ve made some very conservative assumptions in how we
did that. I mean, we couldn\'t distinguish from the results that we got
from the GS flow and meter surveys, which in non-fractured zone, which
fractures are flowing in that zone. It could have been one, it could
have been many. So, we said, okay, we\'re going to say it\'s in the dead
center, there\'s one zone that\'s flowing in the center of that
interval, and that\'s really a pretty conservative assumption.

DIODATO: Thank you.

BULLEN: Thank you, Stephanie. I feel like I\'m the person who calls for
the commercial just before the announcement of the winner of the best
picture at the Academy Awards. So, what I\'m going to do is I\'m going
to make this a twelve minute break, which means everybody is back here
at 2:45, because we all want to hear what Bill Arnold has to say.

(Whereupon, a brief recess was taken.)

BULLEN: Bill Arnold has worked in the area of performance assessment at
Yucca Mountain project for nine years. He\'s been involved in numerical
modeling of groundwater flow, contaminant transport, and probabilistic
risk assessment for several programs at Sandia.

Prior to this, he worked in hydrogeologic research at the Kansas
Geologic Survey, and in the mineral exploration industry. Bill?

ARNOLD: I\'d like to thank Dr. Bullen for working up the suspense here
on this talk. First of all, I\'d like to say that this work is sort of
the synthesis of a lot of work that\'s gone sort of upstream from this
modeling, the saturated site scale flow modeling development and
calibration. Just to mention a few people, George Zyvoloski at Los
Alamos National Laboratories. The site scale transport modeling, Shared
Kelkar at Los Alamos. Perimeter uncertainty analyses that went into this
also is Stephanie Kuzio and Kathy Economy at Sandia. And, then, the
abstraction and interface with the total systems performance assessment
work by Elena Kalinina, Greg Roselle and Dave Sevougian, and others out
here in Las Vegas.

So, if we could have this next slide, this is an outline of the talk.
I\'ll start out with an overview of the approach taken to the total
systems performance assessment and the abstraction for saturated zone
flow and transport. We\'ll go over the assumptions in that modeling
approach and the implications of those assumptions. We\'ll talk about
uncertainty, saturated zone flow and transport for these TSPA analyses.
I\'ll show some of the modeling results, and then we\'ll talk about a
sensitivity analysis that was performed on saturated zone flow and
transport modeling, this subsystem of the TSPA.

This slide is a diagrammatic representation of the saturated zone
component of the TSPA, and I show it principally to point out the
connections between the saturated zone and other components of the
analysis. Radionuclides escaping from the repository would be
transported principally vertically downward in the unsaturated zone to
the water table, then primarily laterally in the saturated zone, where
they would be available for discharge to the accessible environment and
biosphere at some point downstream.

As has been discussed earlier, flow is primarily through fractured
volcanic rocks beneath the repository and upstream in the system. At
some point downstream in the system, that transitions into flow through
porous medium of the alluvium. And, with regard to some of the specifics
in how these components are linked together, radionuclides arrive at the
water table, are put into the saturated zone model. At a point source in
four regions beneath the repository, there was some discussion of this
earlier, there\'s uncertainty in where that point source would be
located. And, that uncertainty is incorporated into the analysis, and
that point is moved around from realization to realization.

Also, the radionuclides are placed into the fractures of the saturated
zone. This is a conservative approach. Radionuclides in the unsaturated
zone model are transported both in the fractures and in the matrix. The
way the modeling is performed in the saturated zone, there\'s not a way
to numerically distinguish between the fractures and the matrix, and it
is conservative to place that radionuclide mass flux at the water table
into the fractures.

However, it\'s probably not as conservative as it might sound at first
glance, because early in the repository history, the first arrivals from
the unsaturated zone will be principally in the fractures of the
unsaturated zone, which would link up presumably with fractures in the
saturated zone.

In the interface with the biosphere at the downstream end of the
saturated zone, all of the radionuclides that cross the boundary of the
accessible environment are assumed to be dissolved in a representative
volume of groundwater at that location, concentration calculated from
those two inputs, and that is the concentration of radionuclides in the
groundwater that would be used by the reasonably maximally exposed
individual in the biosphere.

The general approach that is used here is that for the transport
abstraction in the TSPA, is we use the three dimensional saturated zone
site-scale flow and transport model to simulate radionuclide mass
transport to the accessible environment from a point mass source, as I
described earlier.

We use the convolution integral method to couple radionuclide mass
source term from the unsaturated zone and the saturated zone in the TSPA
calculations. This convolution integral, you can think of as a numerical
shortcut, and there are, I\'ll explain this in more detail in a minute,
and I\'ll also explain the assumptions that go into this method of
coupling the two models. But the motivation behind this is that it
allows us to run this fairly detailed three dimensional site scale flow
and transport model ahead of time for multiple realizations of flow and
transport, save the results from those rather complex model runs, and
couple them to the TSPA analysis through this numerical shortcut of the
convolution integral.

Radionuclide concentration in groundwater source to the biosphere is
calculated by dividing this radionuclide mass crossing the boundary of
the accessible environment by the 3000 acre feet per year, as I also
described.

Climate change is incorporated by scaling the radionuclide mass
breakthrough curves in proportion to the flux changes in the saturated
zone with climate change. So, the model simulations are done for present
climatic conditions. Then, in the TSPA modeling, at the time of climate
change, those breakthrough curves that were derived for the present
climate, are scaled by that factor of the increase in the groundwater
flux in the saturated zone.

To give you the kinds of numbers that are involved here, our estimate is
that for monsoonal climate conditions, that multiplication factor is a
factor of 2.7 times higher. For glacial transition climate conditions,
it\'s 3.9 times higher groundwater flux in the saturated zone.

We also have a separate model which is an abstracted one dimensional
transport model, and this is used for radioactive decay chains. The
three dimensional site scale model does not include the process of
in-growth of radionuclides, only of decay, and for several radioactive
decay chains, we use this 1-D model to calculate the concentrations of
the daughter products at the downstream end of the saturated zone.

This is a figure that represents the model results. The figure here
shows a satellite image draped over the topography, and it is shown
above the water table surface below it. The repository is located about
here. Stephanie Kuzio pointed out some of the features in the site scale
model domain earlier.

The lower part of the figure has projected onto the water table surface
the tracks of, the particle tracks from the numerical model.

One thing I should point out here that I don\'t think has come through
in the previous talks is from beneath the repository out, down gradient
through the system, there\'s a significant convergence of groundwater
flow in the system. We have a gradient that comes in from the west
across the faults to the west and to the south of the repository site,
and a gradient that comes in from the east. So, it is a convergent flow
system. And, there\'s a significant increase in the average groundwater
flux or specific discharge along this flow path from beneath the
repository to the boundary of the accessible environment, increasing by
a factor of approximately five over that distance.

The particle tracking method that\'s used includes all of the transport
processes that Stephanie discussed earlier, advection, of course,
dispersion, matrix diffusion in the fractured volcanic units, and
sorption. And, let me take this opportunity to try to answer one of Dr.
van Genuchten\'s questions about the algorithm that\'s used to implement
the matrix diffusion with the particle tracking.

I haven\'t really prepared figures to describe this in detail, but this
is a particle tracking method that uses a continuum representation of
the fracture network. Linked to that is the analytical solution for
matrix diffusion out of multiple uniformly spaced parallel fractures,
using the Sudicky and Friend analytical solution.

And, the way this algorithm works is for each time step\--not time
step\--for each step of the particle through the system, it travels some
small distance through the cell. We know what the groundwater velocity
in the fracture is. We know what the spacing of the fractures is. We
know what the diffusion coefficient is. All of the parameters that go
into this analytical solution for matrix diffusion.

So, for that step of the particle, we can derive a distribution of
possible transport times between Point A and Point B for that particle
in the system. Then, we draw a random number, uniformly distributed
between zero and one, and we go to that distribution of possible
transport times, taking into account matrix diffusion, and we advance
the particle in time for that spatial step by that amount of time. And,
we do this over and over again for multiple particles, using small
spatial steps through the system, and it reproduces the analytical
solution.

VAN GENUCHTEN: Thanks.

ARNOLD: A couple of other notes. The simulated flow paths from the
repository occur in the upper few hundred meters of the saturated zone,
and Ken showed those results earlier.

The simulated flow paths cross the boundary of the accessible
environment about five kilometers west, northwest of the highway
intersection of the Amargosa Valley. So, approximately in this location
right here, it\'s very close to Nye County Well 19, is where the model
simulations indicate that this simulated plume would cross over into the
accessible environment.

This is a diagram that illustrates the convolution integral method. The
three dimensional site scale model is given an assumed step input for
mass into the system, and then the model is run to derive a breakthrough
curve at the boundary of the accessible environment. And, as I mentioned
earlier, this is conducted for many different realizations of the
system, for realizations of uncertain parameters. It\'s conducted for
the four different source regions, and it\'s conducted for the multiple
classes of radionuclides that are simulated, for which transport is
simulated.

All of these breakthrough curves are stored as a library of breakthrough
curves then. So, this is done outside of the TSPA calculation itself.
The dashed line shows what occurs within the TSPA calculation. Within
that calculation, the unsaturated zone transport model is run, and
generates the output of radionuclides at the water table below the
repository as a function of time. So, this signal of output for
radionuclide mass from the unsaturated zone is convolved with the
breakthrough curve from the saturated zone using the convolution
integral method, and this time varying output of radionuclide mass at
the accessible environment is the output from the convolution integral
that then goes to the biosphere model.

Let me describe at kind of a high level the one dimensional radionuclide
transport model. This is used to simulate the transport of four
simplified decay chains. This is a 1-D representation of the system, and
it\'s implemented directly in the TSPA model using the GoldSim software
with the pipe module. This is a module which can track radionuclide
decay and in-growth, as well, this 1-D model includes all of the
relevant transport processes that we have in the one dimensional model,
matrix diffusion, sorption, colloid facilitated transport. These are all
done in a manner that\'s consistent with the 3-D model.

However, it\'s still an abstraction, because it\'s a dimensional
simplification. It\'s not able to capture all of the complexity of the
3-D model.

This figure on the left shows which radionuclides are simulated to be
transported within the different models. In the 3-D model, we simulate
the transport of all the fission products, and we simulate the transport
of these parents in the decay chains, the americium, plutonium, and
uranium.

Within the 1-D model, we of course have to start with the ultimate
parent of each decay chain, and we simulate the entire decay chain in
the 1-D model. However, the output of the 1-D model in the TSPA only
uses this portion of the decay chains, only outputs this portion of the
decay chains. The upper end of the decay chains are simulated in the 3-D
model.

I should also note that a couple of end members here, I think there\'s
radium 226 and actinium, are calculated to be in secular equilibrium
with their parents in the TSPA calculation.

This is a comparison between the one dimensional model and the three
dimensional model, just to give us confidence that the one dimensional
model is an adequate representation, and we do see that the one
dimensional model gives an accurate depiction of transport through the
system for a wide parameter range.

This figure shows the results of the 3-D model as the symbols, compared
to the 1-D model, which are the lines here, the dashed lines and the
solid line here, for three different cases, a fast case, a median case,
and a slow case for simulated neptunium transport. So, we do get very
good agreement between the 1-D model and the 3-D model.

I should note here, though, that we would not expect this good an
agreement for all realizations of the system. This comparison was
constructed for a source location in the center of each one of those
four source regions beneath the repository, and we\'re not able to
capture all of the variability in the 1-D model, and one type of
variability that we don\'t capture is the variation in the flow paths
and the flow path lengths when that source region at the upper end of
the saturated zone model varies from realization to realization.

Let\'s talk about some of the key assumptions for the TSPA with regard
to saturated zone flow and transport. We\'re assuming steady-state
groundwater flow in the saturated zone, and this has been discussed to a
certain extent earlier. This is an assumption that is probably adequate
for the system. Has not been observed to be a large degree of transients
in the water levels, at least along the\--near Yucca Mountain or along
the flow paths down gradient.

We also assume in instantaneous change in the saturated zone groundwater
flux with climate change. This may be a significantly conservative
assumption. As the TSPA goes through times, we go to wetter climates, so
the groundwater flux in the saturated zone increases with these climate
changes.

In reality, there would be some kind of a transient response in the
saturated zone system. It would take some time for increased recharge to
reach the saturated zone for fluxes to increase in the saturated zone,
but we\'re conservatively assuming that these instantaneously increase
in the saturated zone.

We also assume that there\'s no change in the flow paths. This has been
substantiated to a certain extent by some modeling with the USGS
regional scale model where they did simulate glacial climatic
conditions, and there was no real significant change in the flow paths
from beneath the repository.

The matrix diffusion model is assumed to occur from uniformly spaced
parallel fractures in the fractured volcanic units, as implemented in
the Sudicky and Frind analytical solution. This is an obvious
idealization of the fracture network system. However, we have
significant uncertainty in the input parameters to this that cover a
range of behavior with regard to matrix diffusion.

There\'s also a potentially significant conservatism associated with
this approach, too. We\'re implicitly assuming that flow only occurs in
the fractures of the system. If there were to be significant flow
through the matrix of some of the volcanic units, this would violate
this assumption, but it would also lead to longer transport times and
greater sorption in the matrix through which this advective flow could
possibly occur.

The next bullet has to do with the boundary condition with the
biosphere, which is assuming that all of the radionuclide mass is
contained in this representative groundwater volume usage of 3000 acre
feet per year. This is probably a reasonable assumption. This is a large
volume of groundwater for pumpage on an annual basis, and could easily
capture the entire contaminant plume from beneath the mountain. And,
then, that the average concentration in this volume is released by
pumping to the reasonably maximally exposed individual in the biosphere.
And, this is an assumption that\'s really based on the regulations.

We\'re assuming equilibrium linear sorption occurs in the tuff matrix
and the alluvium. Stephanie discussed this to a certain extent.

We\'re assuming that for the transport of radionuclides that are
reversibly attached to colloids, there\'s local equilibrium among the
colloids, the aqueous phase and the aquifer material. So, this is
assuming a rapid sorption and desorption of radionuclides onto the
colloids themselves, and onto the aquifer material.

For radionuclides that are irreversibly attached to colloids, it\'s
assumed that there\'s no desorption of those colloids during transport
in the saturated zone. This is a conservative assumption. Laboratory
measurements suggest that there will not be a breakdown of these
colloids or a desorption of the radionuclides that are embedded within
the colloids. But, for the very long time periods for transport through
the natural system, it\'s not entirely clear that that\'s a valid
assumption, but it is conservative.

Colloids are subject to attachment and detachment from the mineral
grains, but no permanent filtration of the colloids occurs. So, these
colloids with the radionuclides that are embedded within them, once they
enter the saturated zone, they\'re not permanently filtered out of the
system. They will eventually come out at the downstream end. So, this is
obviously a conservative assumption also.

This is a slide that summarizes the uncertainty in the saturated zone
flow and transport modeling. I have broken this down into uncertainty in
groundwater flow and geological uncertainty. And, the parameters, the
individual parameters of interest here are the groundwater specific
discharge. We have uncertainty in how fast groundwater is moving through
the system. Horizontal anisotrophy in the permeability within the
fractured tuffs is an uncertain parameter. This is significant because
we do have an anisotrophy in the permeability in the volcanic units.
This could steer the path of the plume through different flow paths
towards the accessible environment. We have geological uncertainty in
the alluvium tuff contact in the subsurface. This uncertainty has been
reduced to a large degree thanks to the Nye County Drilling Program, but
we still do have a certain amount of geological uncertainty included
with regard to this.

Now, for radionuclide transport, we have uncertainty with regard to
matrix diffusion in the fractured tuffs, and there\'s several underlying
parameters that are uncertain. The flowing interval spacing that we
discussed earlier, the effective diffusion coefficient in the tuff
matrix, and the flow porosity in the tuff.

We also, obviously, have uncertainty in the sorption coefficients for
the different types of elements in the tuff matrix and in the alluvium.
Dispersivity, both longitudinal and transverse dispersivity, effective
porosity in the alluvium, the source location, the colloid retardation
factor. Stephanie mentioned this is a different distribution in the
tuffs and in the alluvium. We have uncertainty in the sorption
coefficients onto colloids, and uncertainty in groundwater colloid
concentration.

Just to give you an example of how we assess uncertainty in a particular
parameter, and this turns out to be a relatively important uncertain
parameter in the analysis. This is a CDF of our uncertainty in specific
discharge, where this is cumulative probability on the Y axis, and on
the X axis is the log of the groundwater specific discharge multiplier.
So, in log space, a value of zero is our median value. This would
correspond to our calibrated flow model, our expected base case for flow
through the system.

However, we do have uncertainty that goes as high as one order of
magnitude higher, so ten times higher than expected, and to some value
of something significantly less than one order of magnitude lower. And,
the shape of this cumulative distribution function for our uncertainty
is based on results of the saturated zone expert elicitation, and on
more recent well testing at the alluvial tracer complex. And, we have
combined information from both of these sources.

The saturated zone expert elicitation panel had a relatively broad
distribution of uncertainty in specific discharge beneath the
repository. And, that basically defines the bounds of this distribution.

There were several factors that went into their uncertainty in what the
specific discharge would be to the system. There\'s a certain amount of
uncertainty in the hydraulic gradient through the system, but that\'s
relatively minor. Most of their uncertainty was attributed to
uncertainty in permeability, fracture permeability or bulk permeability,
in the volcanic units.

Now, since the saturated zone expert elicitation, there has been this
well testing at the alluvial tracer complex, and Ken mentioned earlier
that we got fairly good agreement between the interpretation of the well
testing at the alluvial tracer complex, and what our flow model was
predicting before those tests were conducted.

So, we viewed this as not only a confidence building, a certain extent,
a validation for the model, we also took this as an indication of reason
to decrease our uncertainty in specific discharge through the system.
And, the bulk of this uncertainty distribution, 80 per cent of our
uncertainty, falls between these two points that are 1/3 times the
expected value of specific discharge, and 3 times our expected value of
specific discharge. But, of course, we left these tails on the
distribution that are taken from the saturated zone expert elicitation.

So, this is the kind of thinking that goes into development of
uncertainty distributions for some of these parameters.

Now, the uncertainty analysis itself, and I\'m sure many of you are
already familiar with how this kind of a probabilistic analysis is
conducted, but it\'s a Monte Carlo analysis in which we sample the
uncertain parameters using a Latin Hypercube sampling method, which is
the method implemented in GoldSim.

We produce multiple simulations, in this case, 200 equally likely
realizations, of groundwater flow and radionuclide transport in the
saturated zone, using these uncertain parameter vectors in the 3-D SZ
site-scale model.

These radionuclide transport simulation results consist as radionuclide
mass breakthrough curves. And, this resulting library of breakthrough
curves is used in the TSPA model via the convolutional integral method.

Okay, these are some of those results for the 200 realizations of our
uncertainty in groundwater flow and transport in the saturated zone.
This is for non-sorbing species. So, this would be for carbon or
technetium or iodine. And, you can see that the results vary over
several orders of magnitude. Many of these breakthrough curves exhibit a
long tail that\'s characteristic of diffusive mass transfer in the rock
matrix of the volcanic units.

Plotted below is a histogram of the .5 breakthrough point, or the median
transport time among these realizations. So, we get this kind of a
distribution for median transport time. And, this red dashed line is the
median of the medians. It\'s on the order of 650, 700 years.

Now, let me take this opportunity to answer another question that came
up earlier, and that was about these few realizations that exhibit very
low, or very short transport times through the saturated zone. And, I
should emphasize again that these are transport times through the
saturated zone, so this is release of the mass at the water table
beneath the repository in the saturated zone.

First of all, to look at this in the context of a probabilistic
assessment, these are all equally likely realizations of the system. So,
these realizations that exhibit very rapid transport are unlikely. We
only have a probability of a few percent, less than 5 per cent that
these transport times would be less than 100 years. So, you have to look
at these results in the context of an uncertainty analysis.

But, to explain what goes into these results, we haven\'t examined these
on a realization by realization basis, but it\'s easy for me to see what
goes into it. These would be cases for which we have a relatively high
specific discharge. We have a relative high value of anisotrophy in
permeability in the volcanic units, which would tend to steer the flow
paths in a more north/south direction, which results in less\--or
shorter flow path length through the alluvium. They probably also
correspond to very minimal matrix diffusion, which is some combination
of the parameters that influence matrix diffusion, low diffusion
coefficient, large spacing between the flowing intervals, so highly
channelized flow in the volcanic. And, then, finally, a potentially low
effective porosity in the alluvium itself.

So, you have combination of fairly unlikely values for individual
parameters that taken together, result in these realizations with the
short transport times simulated through the saturated zone.

Now, these are the results for the transport of neptunium through the
saturated zone. Again, under present climatic conditions, I should note
that all of these results that I\'m going to show you are for present
climatic conditions. And, so, neptunium is moderately sorbing in both
the volcanic matrix and in the alluvium, somewhat higher sorption
coefficient values in the alluvium than in the volcanic matrix. And, the
variability among these transport times extends from less than 1000
years to greater than 100,000 years. And approximately half of these
realizations exhibit median transport times of greater than 20,000 years
in the saturated zone for present climatic conditions.

And, again, you see the histogram of the median transport times among
all these realizations shown at the bottom.

And, just kind of to round out, the range of behavior among these
radioelements, these are simulated breakthrough curves for Cesium, and
if you recall, Cesium is transported via colloid facilitated transport,
the reversible colloid facilitated transport. So, Cesium is subject to
sorption onto colloids. It\'s also subject to sorption onto the aquifer
material. However, Cesium is very strongly sorbing onto the matrix of
the volcanic units, and in the alluvium.

It has a relatively high sorption onto the colloids themselves also, but
still, taken in aggregate, we have, most of these breakthrough times are
out beyond 100,000 years. And, of course, given, for Cesium 137, given
the relatively short half-life of Cesium 137, there\'s essentially a
zero probability of breakthrough of Cesium 137 in the saturated zone, as
predicted by these model results.

I wanted to talk about sensitivity analysis of these simulation results.
You\'ve seen some sensitivity analyses that were presented by the
previous presenters which looked at single model realizations that try
to illustrate the sensitivity of the model to particular parameters or
processes. This is going to be a little more complex sensitivity
analysis. It looks at all of the results in aggregate from this
probabilistic assessment, and in that sense, gives us more of the
sensitivity analysis information all at once. But, it\'s a little more
complex to understand.

But, this sensitivity analysis does provide us with information on the
relationships between our uncertainty in individual input parameters,
and our uncertainty in model predictions. And, in this case, we\'re
using the median transport time from the simulated mass breakthrough
curves as the dependent variable. So, the mid points of those simulated
breakthrough curves are what we\'re taking as our model predictions that
we\'re going to conduct the sensitivity analysis on.

And, this kind of analysis can provide us with an enhanced understanding
of the model behavior, and also valuable information for strategies to
reduce uncertainty in the model predictions.

The method that\'s used is a stepwise linear regression. And, just to
explain this in a very summary fashion, this method constructs a series
of multiple linear regression models that relate the uncertain
parameters to the model predictions.

The stepwise process adds the most important uncertain parameter first
to the regression model. So, the first regression model only includes
one independent parameter. The second step includes the top two
uncertain parameters, and the third step includes the top three. So, you
build up this series of multiple regression models.

What comes out of this is delta R squared. This is the change in the
coefficient of determination with the addition of each new independent
variable to the regression model.

So, what\'s plotted here is the delta R squared for a number of
uncertain parameters for a number of the radioelement classes here. So,
these different radioelement classes are shown by the different colors
or along this axis.

For example, for technetium, or this could be carbon or iodine as well,
this is this first row of results here, and I should point out that on
the next slide, there\'s a key that\'s given that describes what each
one of these input parameters is, but what you can see is that this
parameter, GWSPD, which is our uncertainty in the groundwater specific
discharge, is the most significant parameter for uncertainty in model
predictions with regard to technetium transport through the system. And,
it has a value of about .65, and one way you can interpret this is that
about 65 per cent of our uncertainty in the model predictions is
accounted for by our uncertainty in the groundwater specific discharge
input parameter.

So, it\'s a very important parameter, and if you look across these
radionuclide classes, for many of them, this is the dominant uncertainty
in the system, our uncertainty in just how fast groundwater is moving
through the system is a dominant uncertainty. And, this kind of reflects
back on some results that George Moridis showed yesterday with regard to
transport through the unsaturated zone. I think that a similar result
there also, they have this high infiltration case, expected infiltration
case, and low infiltration case, and he showed the transport predictions
varied over, you know, a couple orders of magnitude for those different
infiltration cases. And, that was the greatest sensitivity that he
showed. So, I think we might have kind of a similar result in the
unsaturated zone and saturated zone here with that regard.

The second most important parameter for technetium transport is FISVO,
which is the flowing interval spacing in the volcanics. This is that
spacing between features that conduct significant amount of groundwater
in the volcanic units. So, the degree to which groundwater flow is
channelized in the saturated zone. And, about 10 per cent of our
uncertainty in model predictions is associated with that parameter for
technetium.

HAVO is the horizontal anisotrophy. So, this is that steering of the
radionuclide flow paths, or the particle flow paths. That does have a
small but significant impact on our uncertainty in the predictions.

And, then, NVF19 is the uncertainty in effective porosity in the
alluvium.

Now, if we move to something where sorption becomes more of a factor,
for example, neptunium, we still see a predominance of our uncertainty
in the groundwater specific discharge, but now we see that the sorption
coefficient for neptunium in the alluvium has a significant impact on
our uncertainty in model predictions out here. We actually see a
reduction in the importance of the flowing interval spacing, because we
only have a moderate amount of sorption in the volcanic matrix for
neptunium.

I could go through several others of these. The really anomalous one
that I should explain here, this is for plutonium, or it could be
americium, it\'s irreversibly attached to colloids, and by far, the most
important parameter here is the retardation factor for colloids in the
alluvium, for the colloids that are irreversibly carrying these
radionuclides through the system. I think that\'s enough on that, so
next slide, please.

And, this is just the key to what those uncertain parameters are in the
previous slide.

So, in summary, the three dimensional SZ site-scale flow and transport
model is used for the radionuclide transport simulations in TSPA. The
matrix diffusion is explicitly simulated by the particle tracking
method. I should note here as implemented in the FEHM software code, in
the SZ site-scale model, these results are abstracted for the TSPA
calculations using the convolution integral method. The 1-D transport
model is used to simulate the transport for decay chains, and
uncertainty in key groundwater flow and radionuclide transport
parameters is incorporated into the multiple realizations of the system.

And, finally, this sensitivity analysis indicates that our uncertainties
in specific discharge and in flowing interval spacing probably have the
greatest impact on our uncertainty in the transport predictions for most
of the radionuclides.

Thank you.

BULLEN: Thank you very much, Bill. We\'ll entertain some questions from
the Board. Do you still want to be first, Dr. Nelson?

NELSON: Sure.

BULLEN: Dr. Nelson.

NELSON: Nelson, Board.

I was struck by Slide 14, and your discussion about the early arrivals.
In many of the characteristics that you cited there in discussion of
those early breakthroughs, and also that you talked about regarding
groundwater specific discharge and flowing interval spacing in volcanic
units and horizonal anisotrophy, all of those things seem to be
characteristics that you would expect if in fact there were fault
directed flow. So, I\'m just working the case, and I don\'t know whether
this is a case of a model uncertainty investigation or a geologic
uncertainty. Maybe in a model like this, changing the geology is kind of
a model uncertainty.

But, I\'m wondering since we\'ve heard from the project that there
isn\'t any clear evaluation of the permeability, the character of the
faults, particularly to the east, and when we see some modeling that
deduces the presence of such high conductivity along faults, as one way
to describe the data, it seems to me that there is a reason to think
about that as a not unlikely occurrence. What do you think about that?

ARNOLD: Yes, I agree that there would be potential importance to the
role of faults in the system. And, there are ways in which we are
implicitly considering the potential role of faults or relatively high
permeability fracture zones in the saturated zone in these analyses.
And, I think the most clear-cut example of that is the horizontal
anisotrophy in the volcanic units. This indicates that there\'s a
relatively high probability that the permeability in the north/south
direction through the volcanic units is higher than the permeability in
the east/west direction, in a rough sense. And, this is substantiated by
pump test results that have been analyzed for anisotrophy.

But, this behavior is probably the result of through-going structural
features of some kind that have a more likely north/south orientation
that gives us a higher permeability in the direction of those major
faults. So, you could say that we are implicitly including the effect of
higher permeability faults through that horizontal anisotrophy factor.

Another way in which we are implicitly considering the possibility of
high permeability faults in fracture zones is this flowing interval
spacing parameter, which has a mean value of 20 meters, as Stephanie
mentioned earlier. But, it has significant uncertainty about that value,
too, and it goes up to values of, you know, tens or even over a hundred
meters, and this would correspond to highly channelized flow in widely
separated zones in the saturated zone that could correspond to this
conceptual model of flow through high permeability faults.

NELSON: Nelson, Board.

What occurs to me is your comments there when you said them related to
these early ones, whether they were unlikely. So, maybe some of the
comment is that I suggest because of model uncertainty, they may not be
so unlikely. There may actually be a reason to consider at this point on
the basis of model uncertainty, the viable presence of these, and their
importance may drive to go find out more about them. But, it doesn\'t
seem that it\'s necessarily something that can be captured by stochastic
distribution, that it\'s really, I mean, it\'s a yes or a no, that may
actually be there. And, so, those early times could possibly, could be
viable reflections of the system.

ARNOLD: They are certainly included in the analysis when it goes to
TSPA.

NELSON: Okay.

BULLEN: Dr. van Genuchten?

VAN GENUCHTEN: This actually is really not a question. I want to go back
to some of the comments I had earlier, and it really was in the
framework, so when you go up, it\'s something like too many things, too
little time, you know, too many questions, or too many things, too
little time to explain, but also for us sometimes too little time to
observe these things. There\'s a lot of material being presented here.

I appreciated your explanation of the matrix diffusion things. It makes
a lot of sense now to me. The other thing here is I understand very well
now that this should be viewed in a probabilistic framework, so it
starts making sense.

The other thing that I was agonizing for about a day and a half about
was the lack of tailing in your curves here on this particular graph.
And, I talked with quite a few people and actually was complaining to my
distinguished colleague here, Dr. Schwartz, but now I understand that
that\'s plotted as a function of log of time. So, it\'s not really
visible, so I finally discovered that. So, a lot of things I struggled
with, finally became clear.

Thanks for hanging in there with me.

BULLEN: Dr. Latanision?

LATANISION: Latanision, Board.

Could we turn to Number 13, Slide Number 13? The last two bullets, could
you just walk me through how all that plays out? I mean, I understand
the concept that you\'re using breakthrough curves as a simulation of
transport. But, how then do you take this library and walk through your
deconvolution\--or convolution integral method? What\'s the process?

ARNOLD: Okay. Yes, what I was trying to explain was some of the
mechanics of actually transferring this information to the TSPA
analysis. So, by a library, I mean here we have a series of files that
contain all of the breakthrough curves from these 200 realizations for
the 3-D model. Those are handed over to the TSPA.

Then, in the TSPA analysis itself, the convolution integral is
implemented by a software code that\'s addressed by the GoldSim software
within the TSPA analysis.

So, for a particular realization in the TSPA, it goes to these files
that contain the appropriate breakthrough curves for that realization,
say for realization Number 1. It reads them into memory, and then when
the convolution integral is conducted by this convolution integral
software code, it takes the appropriate breakthrough curve to perform
the convolution.

LATANISION: Latanision, Board.

What does it actually take from the curve, though? Is it the
breakthrough time, is it the half-rise time, where on the curve are we
interested?

ARNOLD: It\'s the entire curve. It\'s convolution of the entire curve
with the transient input signal from the\--of the mass from the
unsaturated zone. It\'s essentially a numerical integration.

LATANISION: It\'s a numerical integration? I see. Okay. All right, thank
you.

BULLEN: Dr. Leon Reiter, and then Dr. Parizek.

REITER: Leon Reiter, Staff.

Bill, I wonder if you could explain something to me that I may be
misunderstanding. Stephanie showed a plot of saturated zone varied
capability colloidal transport, in which the reversible colloids had
travel times, or breakthrough times, by an order of magnitude longer
than the base case. Yesterday, Bruce Robinson, summarizing the results
of the unsaturated zone, said colloid-facilitated radionuclides had
travel times of 20 years, it\'s like several orders of magnitude less,
shorter, than the other radionuclide.

What\'s causing this tremendous difference between unsaturated zone
colloids?

ARNOLD: Well, I might be sticking my neck out a little bit here without
having Bruce to confirm this. We have, this is for the colloids with
irreversibly attached radionuclides, in the saturated zone, we have a
simple retardation factor for those colloids, and it\'s a significant
retardation factor, and that\'s why the plot that Stephanie showed,
showed the significant delay in the breakthrough for those colloids.
Now, to use that retardation factor, we\'re assuming equilibrium between
the forward rate and the reverse rate for what we know or think we know
is a kinetic process of the attachment of colloids onto the aquifer
material and the detachment of the colloids onto the aquifer material.
And, this is dependent on, you know, transport time scales through the
saturated zone.

In the unsaturated zone, I believe that the time scale for transport
through just the fracture, the fracture continuum, is short enough that
that assumption of equilibrium and the retardation may not be as valid.
Again, I\'m kind of speculating on this one. So, we might really want to
get that answer with some more information from the UZ people.

REITER: So, does this relate at all to the discovery of very high, very
colloidal transport in NTS, it\'s one of the\--being rather rapid, how
does that observation jive with what we\'re seeing here, your
conclusions, Stephanie\'s slide?

ARNOLD: Well, there\'s a lot of uncertainty about why those
radionuclides transported associated with colloids occurred so rapidly,
you know, at NTS. My understanding is that one conceptual model is that
the radionuclides are sorbed onto the colloids by kinetic process that,
given the relatively short time frame over which this transport has
occurred, has not been able to reach equilibrium, and so we have a
non-equilibrium transport of the radionuclides that are sorbed onto
those colloids. That\'s one interpretation. Alternative interpretations
that I\'ve heard, but I\'m not sure if this is still valid or not, is
that those colloids may have some special character associated with the
source of the radionuclides in the underground testing at NTS, that
perhaps the plutonium is embedded in the colloids in some way that is
associated with the source.

BULLEN: More questions, Dr. Reiter? Okay, Dr. Parizek?

PARIZEK: Parizek, Board.

I look at Slide 18, and it has to do with specific discharge and flow
interval spacing. There was not an awful lot of flow interval spacing
data available at one stage in the program. Has there been new tests
from, say, the Nye wells that have added to that data base? And,
particularly with regard to the rocks of choice, that is, below the
footprint within the upward, what, 200 to 300 meters below the water
table, that seems to be where all the action is. So, given those
sensitivities, are there new data on flow interval spacing from the Nye
well, or any other wells beyond the data set we\'ve seen sometime in the
past?

ARNOLD: Not to my knowledge. The data sets that were used were fairly
old. The most recent data that were used in that flow and interval
spacing analysis were from the C-wells. Those are also probably the best
quality data with regard to, you know, vertical resolution. And, of
course, none of the Nye County wells have been drilled or logged really
very near the repository.

I can say that there is one of these S&T initiatives funded by DOE that
is associated with well testing in the saturated zone, and one component
of that is an assessment of the channelization of flow within well bores
and getting at this flow and interval spacing parameter.

PARIZEK: I wasn\'t aware that that was in the S&T program, but that
would definitely be a good starting point to see if you can\'t narrow it
down.

What about the specific discharge? Is there any need to do anything more
with narrowing that down, or do you think you\'ve captured it all in
terms of the way in which you\'ve handled it in the TSP runs you\'ve
done?

ARNOLD: Well, I think we\'ve done a fairly objective job of capturing
uncertainty in that parameter, given the data that are available to us.
It\'s possible that that uncertainty could be reduced by testing
associated with the S&T initiative, or even the full scale testing that
was originally planned at the alluvial tracer complex that had to be
cancelled because of inability to get a discharge permit for that
testing.

PARIZEK: And, Parizek, Board. One other question.

In order to add some comfort, I guess, all the runs always have the
pathways south and eastward, then the alluvium and down, and it would be
kind of helpful, I guess, to list all the other lines of observations
and evidence that support that. I mean, again, the models show that, but
there\'s some chemical data, there\'s a combination of data that sort of
justifies that interpretation, and Priscilla has been bugging you about
many faults creating some surprises, and maybe there are no surprises,
but it would be helpful to list in some clear place where all the lines
of evidence are that sort of says that\'s why the flow ought to go that
way.

I guess it\'s in there somewhere, but it\'s useful maybe to draw
attention to that just to make it clear.

ARNOLD: Yes, I think we\'re, you know, these are very valuable data, the
hydrochemistry data that Gary Patterson presented earlier. There is also
a similar, and in some ways, more extensive analysis of the
hydrochemistry that was conducted by Ed Kwicklis at Los Alamos National
Laboratory, with the specific intent of providing additional confidence
in the flow model. And, so, there\'s a tie between Ed Kwicklis\'s
analysis and his report on the hydrochemistry and the flow model report
that was written by George Zyvoloski with regard to confidence in the
flow paths and the use of the hydrochemistry data.

PARIZEK: That was all C-mixing models, the freak data, that sort of
thing?

ARNOLD: That\'s right.

PARIZEK: Thank you.

BULLEN: Other questions from the Board or Staff? Seeing none, Dr.
Arnold, I guess your little gold statue will be arriving shortly. We
appreciate your hour of presentation to us.

We have to change gears now, and I\'ll start it off by calling on Dr.
Parizek, but just a second.

As we move into the open forum section of our meeting, what I\'d like to
do is ask Richard Parizek to say a few opening remarks, and then we\'ll
call upon our consultants. I want to reiterate the fact that the public
comment period still remains at 5 o\'clock. So, this forum is not for
public comment. This forum is for the technical interchange, and perhaps
to address maybe the five questions, would you like me to put those back
up again, Richard, when you start your remarks. We\'ll have them up
there for that purpose, or any other comments that technical people
would like to make with respect to unsaturated zone or saturated zone
transport.

With that, I\'d like to call on Richard Parizek to say a few opening
words.

PARIZEK: As I chair this Panel, I\'d like to thank each of the
presenters and the organizations that they represent for thoughtful
remarks, and very clear presentations that have been made through the
last two days. It has been very, I think, deals with the questions
we\'ve posed in the advertisement for this meeting, and they have been
responsive in addressing those points.

I know the program probably considers meetings like this an annoyance,
like flies that are bugging you. On the other hand, I think that time
was spent doing this, and discussing and sharing ideas in an open forum
helps clarify points. You have to talk about them, you have to present
the findings. You get different views. It\'s a helpful thing. It shares
understanding with a broad audience. So, I think there\'s value added
from this.

The clarity of presentations were outstanding. The content of these
presentations was outstanding, if you compare this with where we might
have been some years back. So, clearly, we appreciate that richness in
the presentations.

There\'s clearly a transparency also in the way in which the
presentations were organized, and the speakers addressed detailed
points, and proof of that is the fact that the true non-geological
natural systems people, could as such intelligent questions, as you
could see.

We wish to thank Dave Diodato for organizing the meeting, to help pull
together the speakers and other Board members and staff for their
effort, including Linda and Alvina for their work always in making these
meetings work. I think when they go home, their friends think that when
they go to Vegas, this is sort of a junket, but I think they could tell
you otherwise.

There\'s a correction point in terms of the chloride data, the chlorine
36/chloride ratio data. Some of the times, we\'ve seen illustrations
(inaudible) and facts, still current interpretation of the fact. As we
understand it, there\'s still some discussion and some independent work
being done by Gene Kline and others to sort of see is it real or isn\'t
it real. And, so, if it\'s maybe not real, that\'s a final outcome.
Maybe the use of those slides has to be softened, or some other
discussions have to be done there. But, just drawing attention to the
fact we\'ve heard presentations using those illustrations, and if in
fact it\'s been established.

Model validation remains really imperative throughout this whole
process, and we\'ve seen places where the program has tried to get at
model validation, bits and pieces of the field observations, in some
cases after certain forecasts were made, to help lend some credibility
to the whole study. And, I think the program has been quite transparent
in trying to show us how they\'ve done that.

On the other hand, I think there\'s opportunity for further testing that
was not yet done, and the Nye program always talked about a long-term
test in fractured tuffs at some other location other than the C-well
complex, to sort of see whether or not you actually have anything new
that could come out of that, which might include the role of faults.
Surely, there\'s C-well testing in the alluvial testing complex, the
long-term tests that have not been conducted, should be conducted,
because there\'s value to come out of those tests. And, we would hope
that the program can see its way somewhere along the line of getting
that work done.

The sonic drilling has turned up, as some people who have not see the
core, or had a chance to look at it, will be the kind of key to try to
unravel the stratigraphy and the sequence of sediments that make up the
valley fill of alluvial materials critical to performance. So, we
endorse that. We hope there will be more sonic drilling done to provide
the kind of quality information that\'s needed.

The use of multiple lines of evidence, the Board has always asked for
that independent, sort of multiple lines of evidence, the strength in
the TSP analyses we feel everybody can sort of see where this is going
and feel good about it. We still hope that the program works at the
independent lines of evidence listing.

And, we look forward to the confirmation testing program. We haven\'t
heard much about that lately. But, confirmation testing can be tied into
a number of things that deal with the natural system\'s behavior, and we
hope that that program does not ignore some of the natural system
elements that we\'ve heard in the last two days.

We endorse Margaret Chu\'s program on science and engineering, and we
hope that funding is there, and that the program continues. I\'m glad to
hear the discussion that the spacing is included in that, and some other
issues like that. And, we hope that throughout the LA process, and
beyond, there will be a strong science and engineering program.

And, it seems to me the assumptions in the program, at all times
remember when anybody has given us this list of assumptions, it\'s very
helpful to sort of see those up front, because that gives us a basis of
understanding what\'s in and what\'s not in the analysis that\'s being
claimed.

In some regard, the base case, every time you see that solid black line,
you sort of forget, well, what the hell is in the base case. Don\'t you?
So, it might be useful to have the base case listed again, put on the
side so we could always immediately say no, we\'re going beyond that
including these variables in the analysis.

And, my opinion over the years that I\'ve been affiliated with this
program, I\'ve seen immense progress, immense progress in terms of the
natural system elements and pulling together what\'s really a
complicated subject matter, with experiments, state of the art kind of
efforts that have been required, particularly for the unsaturated zone.
Colloids remain a mystery in a sense of how to quantify and capture
them, find out if they really do exist and do move in the unsaturated
zone in particular, because there will be tons of colloids produced from
the repository environment, and it\'s kind of critical to be able to
gain confidence when you understand the colloid story as fully as
possible.

So, these are sort of some points from my perspective, and we can then
go back to Dan and see how he handles this next phase. Thanks.

BULLEN: Thank you, Dr. Parizek.

Would you gentlemen like to make your presentations from the seated
position, or do you want to stand at the podium? Okay. Then, we\'ll go
with Rien, and then Frank.

VAN GENUCHTEN: Thanks, Mr. Chairman.

Actually, this has been a very interesting two days for me. I want to go
back in \'91, I was part of what they at the time called the Yucca
Mountain Peer Review Team, and I still remember convening here in Vegas
with a number of people. Al Frieze was there, and Jim Mercier and
Gresack and Popoudophilis, and a few others, and we were discussing
various mechanisms of how slow fractures could be generated within Yucca
Mountain. They had a lot of fun and drank a lot of beer at that time.
It\'s 13 years ago. That\'s 13 years ago. It\'s now 2004, and it\'s
clear an awful lot of research has been done, and actually, I was just
looking at this special issue of Contaminant Hydrology that was edited
by Bo Bufresson and Clifford Ho and Bruce Robertson. It\'s extremely
impression, and I think, Richard, you mentioned that. It\'s awful, how
much has been done over the last so many years.

But, it also shows how complicated the system is. This is not something
that\'s going to be resolved in an easy manner, or in a great manner,
and it\'s very important to keep understanding that these scientific
issues will be at the table for quite a while to come. And, actually, in
a way, it was fun yesterday especially to see us starting to discuss
again, like we did in 1991, the various mechanisms of how flow in
fractured media are generated and sustained. And, so, we had a lot of
discussion, you may remember from yesterday, about different
conceptualizations of matrix fractures, fracture interactions in terms
of unsaturated flow in the mountain.

And, I think it\'s important to realize that, and this goes a bit back
also to some of the comments of Bredehoeft about uncertainty. These are
really conceptional uncertainties we\'re still struggling with.

I completely agree with the approach that was taken in terms of the
active fracture model as an attempt to include in the models the idea
that there is limited contact between unsaturated flow in the fractures
and the matrix, and that\'s a conceptional picture, a conceptional
model. It\'s still going to be a question how that\'s been translated
into a mathematical model, and I can see several different formulations
arising from that, not just the power function of relative saturation,
of effective saturation that was used in the models of Liu and all.

So, there are still a number of uncertainties in terms of conceptional
formulation, and how that translates in models. The similar way is
we\'re going to even go back a step before that, and say is this really
a contact problem, or maybe I tried to push that yesterday, a problem of
maybe having coatings in there and limited interaction between the
fracture matrix, not because of necessarily limited contact area, but
also limited, lower values of the effect of conductivity of coatings,
not necessarily coatings that you can see, but there may be some stuff
below the surface literally that inhibit this effective interaction.

And, similarly, it has an effect on matrix diffusion. These are things
that need to be pursued. I think it\'s important that not just one
formulation be pursued, but that there is room for different
conceptionalizations, different conceptional models, not everything
should be, you know, all the eggs in one basket.

There are a large number of people here with enormous backgrounds,
impressive conceptional reasoning. when we do a big experiment like that
that costs us several hundreds of thousands of dollars, I think it would
be very cheap to put a few good\--on the computer and let them get the
most out of it.

And, this actually is similar comments, I think, are important also for
other issues, that lateral flow there, we talked about in the PTn unit.
Some people claim it\'s very little. There\'s still a little bit of a
legacy of earlier investigations that that might be quite important. I
think getting some people together and looking at these issues is
important, and let\'s resolve it as best as we can.

I probably have a few other things. I\'ll pass those up. I want to
thank, in closing here, I want to thank the Board for inviting me. This
was just extremely educational for me, having not really been involved
with Yucca Mountain for about 12, 13 years to see the excellent signs
being done. I want to thank all the people that gave presentations. It
was just great, and thank you so much.

BULLEN: Thank you, Rien. Dr. Schwartz, did you want to sit at the table
or stand at the podium?

SCHWARTZ: I\'ll sit.

BULLEN: Okay.

SCHWARTZ: Well, like Rien, I\'d like to express my thanks to the Board
for the kind invitation. In my real life, I\'m a professor at Ohio
State. My work at Yucca Mountain has been carried out mostly with EPRI
and John Kessler\'s group at EPRI. I\'ve worked in various DOE panels
dealing with thermal testing and the Nevada Test Site in general.

There\'s some real benefits of being a Panel member here. As I\'ve
looked out into the crowd, one of the things is that with my age and
vision here, I\'m actually close enough to the screen to see the
presentations, and as I\'ve been wandering around the room, we up here
get these nice color copies, as opposed to the black and white ones
there.

There\'s some disadvantages, too. As I\'ve kind of looked out in the
crowd periodically, you\'re able to doze off there periodically, so one
of the down sides of being a Panel member here is that it\'s hard to
doze off up here.

I\'d like to follow up on some of John Bredehoeft\'s comments. He kind
of opened Pandora\'s box for discussing issues of philosophy related to
modeling. That\'s an area that has been of some interest to me, not only
so much for modeling, but looking at sort of the philosophy of science
and related to progress in the hydrologic science in general. I actually
have a Ph.D. student at Ohio State that kind of works on this issue.

John Bredehoeft, you know, talked about this issue of surprise in
science, and one of the points that maybe didn\'t come out in his talk
is that surprise in science is really a normal process. And, it\'s a
normal process in the sense that that\'s the way most progress is made
in science.

Matt Kozak in his brief remarks talked about Thomas Koon and the idea
that he had, and there are important ideas he had about the idea of
revolutionary science versus normal science. And, I think John
Bredehoeft gave a very good example there that, you know, this idea of
plate tectonics, when it comes time for some prevailing idea to be
overturned, that often times, there\'s a revolution or a culmination or
a collection of ideas that come together to overturn that idea. And, so,
a step forward in science occurs through a revolutionary step forward.

But, after that revolutionary step, there is this process that Koon
calls normal science, and that\'s the day to day plugging along, taking
care of all the details, doing the fundamental work, and so on. So, I
think, you know, the work at Yucca Mountain is no exception, that we see
the progress in the science measured by some revolutionary steps
forward, which turn out to be surprises, you know, from the DOE
perspective probably not happy to see them, but in the overall
perspective, it shows that the progress of science is surely marching
on.

Now, one of the things we see in hydrology, is we\'ve studied this idea
of evolution in science idea, is that we usually don\'t see so many
major surprises. They\'re more like paradigm shifts, or some kind of
disruption of the status quo. They\'re not quite as severe as all of a
sudden waking up one day and discovering plate tectonics. But, these,
nevertheless, these revolutionary steps are important, and they are the
normal way in which new knowledge is developed.

Now, I think there\'s been a history of surprises in the science at
Yucca Mountain, revolutionary changes. I think Alan Flint\'s discovery
of high recharge rates back in the early to middle 1990s would qualify.
Fabryka-Martin\'s chlorine 36 information, whether it kind of stays or
goes, still ranks as an important generator of revolutionary idea. I
think there have been other important areas where there have been some
important revolutionary steps.

On the modeling side, I think the work at LBL in identifying the unique
characteristics of the Paintbrush non-welded unit and the basal
vitropheres, some of the unique properties that they have and some of
the important things that these units do for transport of gases,
transport of contaminants, and so on.

So, my view, like Rein said, is that Yucca Mountain is a very complex
applied science problem, and as I sort of began my work with EPRI in the
late 1980s in this project, clearly, if you look back over those 12 or
15 years, you\'ll see the tremendous advance in theory. You know, in
retrospect, probably the theories we had for flow in fractured media was
immature and not sufficiently robust to describe the kinds of systems we
talked about.

But, I think as I\'ve sat here over the last two days, I guess I\'ve
been really impressed by the maturity of the science ideas that have
been developed, in really looking at the major advances in developing
the really the intellectual tool kits necessary to support the
calculations to support the basic theory. So, I think there is some
important progress in that respect.

Now, the question kind of, John\'s talk implied that, and some of the
others, is really can one analyze complex systems subject to
uncertainty, and that uncertainty, as we\'ve learned, comes in the way
of processes and parameters and future states, and we\'re not sure of
any of those things particularly well. And, clearly, the answer has to
be yes. I mean, if you think about what geologists, engineers,
hydrologists, and metallurgists do, I mean, that is what the kind of
engineering analysis is all about, to make decisions with relatively
limited data sets, insights, experience, and so on.

And, the evaluations here that we\'ve seen have involved simple tools,
simple calculational tools, some pretty sophisticated model analysis,
and all of that is checked by sort of seat of the pants engineering
concepts, and trying to provide for what I consider to be coherency of
results, so that if you make one model conclusion, do other processes
and other observations fit well with that conclusion, and that\'s sort
of a coherency that one model can explain several things.

And, I think the work that Bo Bodvarsson and his group at LBL, and
colleagues with the USGS and the UZ, I think they\'ve shown that
there\'s pretty good progress in actually providing the coherency of
results that there started to be needed to create confidence that the
understanding is in reasonably good shape. And, I cite for that some of
the material we\'ve seen here would be the geochemistry, the occurrence
of perched water. Some of the things that we didn\'t see here would be
sort of air flow calculations, and these things as well.

So, I think in the unsaturated zone, there is good progress, and you
have a feeling, at least I do, that the modeling is moving in a good
direction, that the surprises would be minor, and hopefully will be in
the normal science phase.

I think in the unsaturated zone, my feeling is that the results are
conservative, that I think there are performance benefits yet to be
wrung out of the saturated zone.

However, as we look at the saturated zone, I think what performance
there is, even under the conservative assumptions, are very helpful to
the safety case. I think that the sorbed species are extremely retarded
within the saturated zone. I think the unsorbed species have meaningful
retardation. So, I think even at this stage, the saturated results are
pointing towards some certainly advantage as far as the safety case is
concerned.

My own impression of the interpretation of geochemical data is in line
with the question I asked Gary, that I\'ve written similar kinds of
things, I think the geochemistry and the isotopic data support a much
more sluggish kind of flow system, and I think there is still some
inconsistencies. I think in the saturated zone, there may be room for
surprises, but I expect they will be pleasant surprises as far as the
safety case is concerned. I think there\'s, you know, opportunities for
improving things certainly, but given that they\'re relatively
conservative now, I think the possibilities of degradation in that
safety case is probably minimal.

And, so, again, thanks. I appreciate the audience staying.

BULLEN: I\'d like to thank Richard and our consultants for their opening
comments, and now I\'d like to ask anyone who\'d like to either come to
the podium, or to the open mike, to step forward and make comments on
anything that they\'ve heard in the past two days, or the questions that
we\'ve listed and were posted. Go ahead, feel free to step forward,
whoever wants to be first, and identify yourself.

MIFFLIN: I\'m Marty Mifflin, and like others here, I find this a very
interesting and improved type of review of both the vadose zone and the
saturated zone hydrology. My background is as follows. I first became
acquainted with the Yucca Mountain repository proposal in 1981 as a
consultant for NRC, and over the years, went from NRC to technical
oversight with the State of Nevada, and with a contractor for Inyo
County and Nye County as well for a period of time.

So, I saw the early days, and I remember the smoke filled room back in
Silver Spring, Maryland in 1981, sitting around with the various gurus
that had been called in to try to decide what NRC\'s position should be
with the vadose zone, and what should be looked for. And, one suggestion
was that, well, let\'s just treat it as a black box, and worry about
what comes out beyond the disturbed zone, the so-called disturbed zone
at that time, which would be some type of definition of the edge of the
thermally disturbed area.

And, surprisingly enough, there was quite a few people that, when I say
quite a few, of the ten or fifteen in the room, a fair number thought
that was a good idea. I thought it was a very poor idea, primarily
because you didn\'t quite know what was going to come out if you didn\'t
know what was going on in the inside of that black box.

One of the things that I wanted to say is that right now, nobody is
supporting my work on this, and, so, I can say exactly what I believe. I
think the site is a very poor site, because of its complexity. We\'ve
heard two days worth of very complex analysis, yet for the most part,
they have to be heavily dependent upon poorly constrained conceptual
models.

Now, a lot of the presenters felt that their analyses were conservative.
But, conservative in one man\'s view may not be very conservative,
whereas, the other person may think it\'s a very conservative analysis.
It\'s a very subjective type of evaluation.

I\'ve had a whole series of conceptual models in my own mind\'s eye over
the years, and they\'ve quite often differed with the popular conceptual
models over those various periods of time. I might add that most of
those models that I thought were more realistic have come closer to what
has been determined over the years.

The other thing I\'d like to remind the Board in particular is that the
focus is on the right questions at this point in time, far better than
it has been at any time in the past. However, the data bases and the
funds that were expended in developing those data bases are not very
well designed in many areas because of the nature of the field data base
programs.

For example, we heard some type of description of how many wells were
available at such and such a time, something like 40 mentioned, and most
of those at that point in time, which was in the Eighties, were drilled
with water based fluids. Here, we have a repository that was supposed to
be a dry repository, and the data base very critical, determines just
how dry is dry. And, so, a lot of these data bases, which the current
experts are trying to utilize on some fairly sophisticated type of
questions, are not really designed for those types of analyses.

For example, the hydrogeochemistry, we\'ve got boreholes that are being
used that are several hundred meters of open borehole in the saturated
zone, and we\'ve got some that have less than, say, 50 meters. And, we
have a very complex way or type of volcanic sequence, and if you go back
and look at the early testing in the saturated zone, H-1 and the G hole,
you\'ll see that there\'s very, very highly transmissive zones, but very
few of them. And, the head data is based on some type of average head.
So, you don\'t really know, in other words, all the testing, and so
forth, went on after the hole was completed and cleaned out, and so
forth.

So, there\'s a lot of uncertainty in what, say, water chemistry means,
if you have any type of stratification. And, one of the points made was
that maybe a three dimensional, an attempt at three dimensional
hydrogeochemistry was appropriate. But, for 15 years, nobody worried
about that. And, that goes for most of the saturated zone and the vadose
zone.

Another point I\'d like to raise is that I watched an evolution, this is
more philosophical, but I think it should be said, I watched an
evolution of not only the site selection and licensing criteria, but
also the effect it had on the scientists addressing the site
characterization and analysis. It started out with an agreed upon site
selection guidelines between NRC and the Department of Energy, and these
were pretty reasonable. It also had, you know, the key licensing
criteria, which was the groundwater travel time. And, those were\--there
was site selection criteria, and then there was the fundamental bottom
line licensing criteria, which was related to groundwater travel time.

That approach has changed, but one of those site selection guidelines
was a very important one, and everybody has forgotten what it was. And,
that is site complexity, had to be confident in your characterization
and analysis of performance. Everybody has forgotten that.

Well, right from the start, the selection of the unsaturated zone, the
vadose zone, as I like to call it because it has water, was taking an
unknown environment in terms of either what process is going on, as well
as how do you determine those processes and get the data bases, and that
was, in a way, a fundamental mistake, because we still don\'t have great
confidence in the details of the processes.

And, you know, fractured volcanic terrain where you have welded,
embedded and altered tuffs is also a fairly complex saturated zone
environment.

I\'ll make a specific comment of what I heard on the saturated zone. The
hydrogeochemistry was recognized as some variations way back in the
maybe Sixties\--or mid Eighties, I\'m sorry. And, what has been noted is
maybe you have a stagnant type of situation, less active flow in some
areas. The other thing that I\'d like to point out is that just because
you have gradients off to the east doesn\'t really mean in these
fractured terrain areas that you have flow. These very steep gradients
raise and issue, and one of the big surprises in the early
characterization studies was drilling a hole up on top of the mountain
and finding out that you were still, on the east side of Solitario
Canyon, and finding out that you were still on the high part of the
fluid potential. So, in other words, it was in the wrong spot for the
fault to be causing the marked difference in fluid potential from east
to west.

In my, in one of these alternative conceptual models, in my opinion, is
the flow is right down all of the faults, more or less north/south. If
you go back and look at the hydrogeochemistry data base, that\'s pretty
well supported. Now, the NRC modeling that we saw just assumed that the
gradient is down, or the flow is down the gradient, and if I heard him
correctly, he said it was isotopic and homogeneous type model.

Well, in fractured rock terrain, that type of modeling is not a very
good characterization, as far as I\'m concerned. It just is too large of
an assumption. And, one of the things that NRC worried about in the
early days was how to characterize the saturated zone. Many of the
consultants to NRC at that time thought that there had to be multiple
well testing, not just the C-wells, but pump testing to find out whether
or not these faults were barriers, or not barriers. And, that never
happened, but over the years, the people\--this has been going on so
long, that there\'s so many different people involved, the human element
comes in and there\'s no real institutional memory involved from early
to intermediate to later to later thinking on how to characterize the
site.

There\'s another key point here that I picked up that I\'d like to
comment and alert the Board to. That is that we heard quite a bit about
climate change. We\'ve heard some numbers on what the monsoonal and
transitional climate impact is on flux. If I recall correctly, one was
the monsoonal was 2.7 times estimated current flux, and the transitional
was 3.9.

Very early on yesterday, we heard the terminology effective moisture.
Effective moisture is an important concept, not very well defined, but
what it really means is what\'s left over after all the
evapotranspiration occurs\--well, what it originally meant was the
following, because I defined it. In looking at these Paleoclimate,
Paleohydrology that resulted in the hydrographically closed basins in
the Great Basin, there was a whole series of pluvial lakes that
occurred. And, these pluvial lakes were in the bolsons (phonetic),
somewhere up along the sides, most extended only onto the bahadas, and
if you measured the amount of moisture that came into the lakes to
maintain a stable lake level, the high shoreline, what you were
basically doing, if you assumed any rate of evaporation off the lake,
you had a hydrologic budget from the catchment basin to the discharge,
which was direct evaporation from the lake. And, it was independent of
precipitation, and it\'s independent of, as far as a direct measure, of
either precipitation or of temperature, or of a whole series of other
factors that might influence the size of that lake. But, it was clear
that you had effective moisture that maintained the lake.

Now, what is important in the flux through either the vadose zone or the
saturated zone is effective moisture, not what the details of the
climate are. It\'s just how the flux changes. Well, one of the really
interesting things in the Great Basin and why I pick up on these
relative factors is that all through the northern part of the Great
Basin where you have the lakes, and in a few areas, you have modern
lakes, where you have modern estimates of groundwater discharge where
there is no lakes, you can go back and you can compare the full pluvial
climates, lake size, compared to the catchment basin, with the modern
pluvial\--the modern climate discharge. And, you find out that these
differences in effective moisture ranges from about ten times to about
15 times. Okay? That\'s the whole pluvial climate.

Now, if you look in these basins carefully, by the way, these pluvial
lakes stop just north of the latitude of Yucca Mountain, the
southernmost one is Gold Flat, a little bit to the north, if you look
very carefully at these basins, and a lot more work has been done in
recent years, you have both the last full glacial type shorelines, and
then you have the younger driest type shorelines, which is more or less
assumed to be associated with more of a monsoonal type warmer, wetter
type of pluvial period, almost 2,000 years. And, somewhat earlier, you
had, based on packrat midden evidence, you had a much drier, but colder
type of full glacial climate, last full glacial climate.

The lake levels, however, based on those shorelines, are very, very
similar. The younger, driest lake level, or high shoreline, is usually,
for all practical purposes, if you\'re measuring an area in the basin,
the same number, but it\'s a little lower.

So, I think that the Board, and actually the Project, should look a
little more carefully at how they\'re coming up with their climatic
flux, both through the vadose zone and through the saturated zone. I
also noted in this last talk that the flux is rather important with
respect to what type of actual numbers you get in terms of the
sensitivity analysis.

So, if it\'s not\--if it\'s three times, it\'s one thing. If the current
flux is 3,000 acre feet a year, and it was 30,000 acre feet a year,
that\'s another thing during the full climate, pluvial climate.

BULLEN: Marty, are you pretty close to wrapping up? Because we\'ve got a
couple more people I think that probably want to say a few things.

MIFFLIN: Okay.

BULLEN: You\'re like the professor. We give you any time, and it turns
into 50 minutes.

MIFFLIN: I want to say one more thing.

BULLEN: Okay, that would be great.

MIFFLIN: Because we\'re changing the regulatory\--this is in response to
the gentleman from EPRI, I forgot who it was, because we changed the
regulatory rules on this thing, at that point in time, I decided, well,
let\'s go back and base everything on, from the scientific perspective
of what the objective was with deep geologic disposal of high level
waste. And, I think it\'s worthwhile for the Board to keep that in mind.
There are the regulatory issues, but there also are the true objectives
of the program.

And, the reason that the National Academy of Science, if you go back and
read that document, or that recommendation, the reason that they
recommended deep geologic disposal was to isolate the waste from the
biosphere, because of the long-lived nature of the waste.

I think the site is a bad site from that perspective, because it\'s
emplaced in the biosphere. As soon as the first canister fails, you have
gas phase release into the biosphere within months, based on the air
circulation evidence, and within, certainly within the inventory life of
the majority of the radionuclides, if you have an engineered barrier is
the only barrier, and relatively short travel times, then you have
discharge back to the land surface. Anything that isn\'t absorbed is
going to come right back to land surface.

And, these pluvial climates, and the intervening climates, which are the
transitional and the monsoonal climates, make up both of the future
based on the Milankovich idea. It\'s something like up to 70 per cent of
the future.

So, we have the radionuclides that are long-lived coming back to land
surface, and then they spread around. And, I don\'t think that\'s what
the intent was of the National Academy of Science.

So, that\'s my comment.

BULLEN: Thank you, Marty. Anyone else like to make a few comments? I see
George approaching the microphone. Would you like this one, or do you
want the front one? I\'m comfortable sitting here, so I\'m just going to
stay. So, why don\'t you go right ahead. Identify yourself, please, and
your affiliation.

HORNBERGER: I\'m George Hornberger, I\'m a professor of environmental
sciences at the University of Virginia, and even I\'m a professor, I
won\'t take my full 50 minutes.

BULLEN: Thank you.

HORNBERGER: First, I wanted to say that I first got into notions about
the disposal of radioactive waste in 1980 when I was asked to serve on a
National Academy Panel that had been asked by the Swedish Program to
review the KBS3 plan. The KBS3 plan was important, because the Swedes
had actually, in law, determined that unless they could show with
absolute certainty the safety of geological disposal, they were going to
have to shut down their electricity generating plants. And, of course,
the scientists on the NRC Panel, National Research Counsel Panel, were a
guest at this. We said, well, we may as well give up now, because we
know there is no such thing as absolute certainty.

Fortunately, of course, the Swedes took the legal system, takes a
pragmatic view of what absolute certainty means, and moved forward.

Now, fast forward. One of the things that I do is I serve for the
Nuclear Regulatory Commission, the other NRC, on their Advisory
Committee for Nuclear Waste, the ACNW. The regulation for the NRC, as
everyone knows, is not absolute certainty. Thank goodness. I don\'t have
much confidence that our legal judicial system would know exactly how to
handle that. It is reasonable expectation, and I think that it\'s worth
keeping that in mind.

Again, as a professor, I can\'t avoid now that John Bredehoeft opened
the door and Frank Schwartz walked right through it in terms of
philosophy, because professors just love to pontificate on something
they know very little about. But, in the 1970s, John Phillip, who is a
famous soil physicist from Australia, wrote a paper on prediction in
catchment hydrology, and that\'s a problem basically you might picture
it as trying to predict or forecast the fate and transport of
agricultural chemicals from a catchment. And, John Phillip pointed out
that this was a problem that could certainly be formulated as a rigorous
scientific question, and actually, you could address it in the standard
hypothetical deductive procedure.

Phillip went on to say that if one did that, the benefits derived from
actually doing the necessary measurements would be tremendously small
relative to the expense that one would have to undertake to do this as a
scientific project. Some of my more cynical friends would say that Yucca
Mountain actually illustrates Phillip\'s point very well.

Phillip didn\'t, of course, throw up his hands and say that this meant
that science didn\'t have a place in such projects. It obviously has a
place, and rigorous science has a place. But, one can\'t approach these
things in the same way as one would design a research program.

So, what we\'ve been, I think, discussing here, all of the discussions
and all of the questions that the Board posed, are basically oriented
toward how one goes about looking at reasonable expectation. I think,
like what people have expressed here, I\'m quite impressed with the
progress that has been made.

I did have my\--the biggest question I had actually Leon asked for me
right at the end, and that was that if I go down the list of questions,
the last two there, what is the technical basis for estimates, and how
much could the technical basis be improved, I was struck by the colloid
transport materials we heard. There was precious little that I saw in
the way of the technical basis. That is, I didn\'t see very much data. I
didn\'t understand what the technical basis was for a 20 year travel
time in the unsaturated zone and thousands of years retardation in the
saturated zone. I don\'t anticipate, because Leon didn\'t get an answer
to his question, I don\'t anticipate that I\'ll get an answer to that
question, but I think it is something that really does deserve the
Board\'s attention.

Thanks.

BULLEN: Thank you, Professor Hornberger. Any other people who would like
to make comments, please come forward and identify yourself. And, you
can have either podium or microphone.

FISK: Good afternoon. I\'m Terry Fisk. I\'m the hydrologist for Death
Valley National Park, and I didn\'t know I\'d have the opportunity to
have this weapon of microphone in front of me today, but I\'ll try and
behave myself.

And, I also want to go back to John Bredehoeft\'s talk this morning, and
Dr. Parizek\'s comment. And, first of all, I\'d like to say that the
Park Service is getting immense value out of the work that Inyo County,
through the hydrodynamics group is doing, and also we support a very
small degree financially, the USGS flow system model, and the research
that\'s gone on at Yucca Mountain. So, I\'d like to get that on the
record.

Despite the support for that, and looking at drilling within the park,
we can definitely be a pain in the ass, even to those projects that we
would like to see go forward. I would certainly like to see some work
done to further flush out the mapping that Chris Friedrich has done, and
the modeling that Dr. Bredehoeft has done.

To make that happen, we go back to the Organic Act of 1916, and the
purposes for which the park was designated in the enabling legislation,
and so on, and that means following the National Environmental Policy
Act, and so, logistically, it\'s difficult, and policy-wise, it\'s
difficult, but it\'s not an insurmountable issue, and I would like to
try and work with Inyo County on making that happen. And, if the Board
could see its way at some point, it might be a letter might be advisable
on the record in support of that. So, I just wanted to make that point
and get that on the record, that we do support that work.

The other issue that I wanted to get at a little bit is the one that
John also mentioned, and this I put in a memo about two and a half years
ago to the Water Resources Department of the National Park Service in
Fort Collins. I don\'t think it had wide distribution from that group.
But, the idea that there is a head difference right now, an upward
gradient from the lower carbonate aquifer into the volcanics, and one of
my concerns, and that of Death Valley as a whole, irrespective of Yucca
Mountain and radionuclide transport, is potentially use of that
carbonate aquifer as a water supply for the municipalities in the region
who are actively looking at that as a water supply source, and, so, a
danger that I see and others have seen is reversal of that gradient,
which is a factor both for protection from contaminate transport and
also for protecting flow to the springs in Death Valley.

And, I think that\'s\--I\'ll stop there. Thank you very much.

BULLEN: Thank you. Other members who would like to make technical
comments? Linda, please come up and identify yourself.

LEHMAN: Thank you, Dr. Bullen.

I\'m Linda Lehman, and I think most of you know that I work for the
State of Nevada. I haven\'t given a presentation to the Board in a
couple of years, but I think there\'s still a critical mass of Board
members who remember my models that I presented to you on behalf of the
State.

The thing that struck me today was that we see what we want to see, and
we hear what we want to hear. I heard Bill Arnold say yes, he feels the
lines of evidence support his flow path. Well, I also heard the same
thing. I feel that a lot of things that were presented today actually
support the more southerly flow path that I have presented to you
several years ago.

I also wanted to thank Jim Winterle for his excellent presentation, and
I would like to, I don\'t know if we can use any of those slides from
that. I\'m thinking about his representation of the alternative
conceptual models, and it\'s this one. Page 11. Anyway, I think his talk
illustrates a number of concepts that I was trying to present in my
models some years ago. He shows that the flow from the repository moves
to the east until it intersects the first fracture zone. And, his first
fracture zone is the Bow Ridge that he\'s combined, Midway Valley.
That\'s basically the same concept that I was trying to illustrate.

The only difference between what I see he is presenting and what I have
presented to you in the past is that I included the Ghost Dance Fault,
and the Ghost Dance Fault lies just to the west of the Bow Ridge. So, in
my model, you would have movement from the west to east until it hits
the Ghost Dance, and then comes down more in the middle of the mountain
block.

If the Ghost Dance is being transmissive and carrying things to the
south, I\'d like to remind you that the largest part of the repository
mass is on the west side of that. You may have, I haven\'t seen the very
latest plan that you mentioned earlier, but the one that I saw, the
biggest part of the fuel is stored on the west side of the Ghost Dance,
and there is some being stored on the east. Those radionuclides that are
on the east side would probably move as Jim has shown in his
presentation, to the east. So, that I thought was quite similar to what
I had been trying to get across in terms of concepts.

The other thing that I would like to bring up is the coupled heat flow
calculations that were presented by Dr. Rehfeldt. And, the particular
graphic, I have it marked here, I\'m just trying to find the page
number. Number 16. And, I can\'t see too well from this graphic that we
had, but it looked to me like he was making the case that conduction and
convection is important for the lower part of the model, but he didn\'t
feel\--he felt he had a good enough match, basically, in the top part of
the flow field. And, I guess I want to disagree with that, if I\'m
reading this correctly, it looks like, to me, the dots in the northern
part of Yucca Mountain are anywhere from 3 to 10 degrees C. off from the
actual measured values.

And, across the region, there\'s only about a 4 degree spread in
temperature if we believe Sass\'s temperature model. And, unfortunately,
there wasn\'t one presented today. But, the reason I chose to use the
Ghost Dance fault, and some of you remember, is that there appears to be
a cold water finger that moves down the Ghost Dance Fault, at least
it\'s centered on the Ghost Dance Fault on the maps, a cold one again
through Crate Flat, and a cold one through Fortymile Wash.

So, I feel that his temperature representation does not support his
model of flow path, and I would think that they would have some
additional work perhaps, doing calibration, or whatever, to try to
correct that. And, if I read this correctly, it looks like the
temperatures are about 3 to 10 degrees too hot, which would indicate
that they maybe don\'t have enough cold water coming in to cool the
upper units. And, they could also use as calibration data Sass\'s heat
flux distribution as well.

That\'s it.

BULLEN: Bullen, Board. A quick question before you go, Linda, because
I\'m not a hydrogeologist and I\'ve asked all these questions anyway, so
that never stops me, but as I saw some of the lines of constant head
that we\'ve seen, or for the flow field development, it looked to me
like there were some of the embayments that you presented to us maybe
two, three years ago kind of creeping into that. Is that\--do I
misinterpret?

LEHMAN: No, I saw that in Dr. Winterle\'s presentation.

BULLEN: Okay.

PARIZEK: It\'s Page 7 of Winterle\'s graph.

BULLEN: Oh, okay. Thank you, Dr. Parizek.

PARIZEK: The other interpretation smooths that out. But, he sort of
followed the data, so I\'m not sure what data is different here than
what maybe you saw sometime ago. Apparently, you complained about him
having left out the wiggles. This is conceptual if you argue the faults
and the washes are enhanced permeability, it\'s how you might be
inclined to make the wiggles, unless the data says you should put the
wiggles in. We almost have to see the data again to see why this
interpretation exists.

LEHMAN: Okay. What I used to use as my justification was the USGS water
table maps. When they recalibrated the water table surface and releveled
all those wells, they did not use all of the data points that came out
of that analysis. Some of them were left out on the basis that there was
no physical reason that they saw to use those lower head values.
Granted, they\'re very small, hundredths of a meter, but still, if
you\'re going to believe the rest of the data, it\'s nice to believe all
of the data. So, that\'s where I got them. I contoured all of the data,
not selective.

BULLEN: Thank you, Linda. Anyone else from the audience want to comment
on the forum portion of our presentation? Or all you all thinking if we
get done 12 minutes early, I can beat traffic home? Don Shettel raises
his hand. I couldn\'t get out 12 minutes early with Don in the room. So,
come on up. Identify yourself, please.

SHETTEL: Don Shettel for the State of Nevada.

It\'s hard to follow the first two philosophical talks here, because
I\'m going to get into the nitty gritty I guess, but somebody has to, I
suppose.

The three points here, the first one involves the drift shadow effect,
and I must say that even the conceptual diagram of this is a little hard
to believe, because if the matrix gets saturated in places there, that
would seem to lead to fracture flow. And, at least my main comment on
this, which is a comment that Dr. Bodvarsson made about a year ago at
this meeting in the Long Street Inn, where he said there were billions
and billions of fractures in the vadose zone, and we can\'t put which
ones are going to flow. So, how does he know there\'s going to be a
drift shadow? Those two concepts seem to be incompatible.

Now, the second point involves sorption coefficients. In the first set
of AMRs that came out three or four years ago, there were ten\--there
were a number of assumptions, but there were ten assumptions that
involved sorption coefficients, and essentially DOE said all these
assumptions needed to be confirmed, and one of these assumptions was
that the sorption coefficients in the saturated zone will be the same as
for those in the vadose zone. But, all the experiments were essentially
saturated experiments. So, my question is essentially to the DOE, have
they confirmed this assumption, and where is it located?

And, the last point would be diffusion coefficients and flow in the
unsaturated zone, and specifically I\'m referring to George Moridis\'s
talk yesterday where he supposedly had some very conservative
assumptions regarding essentially one on performance assessment, I
believe it was, looking at just flow in the fractures in the vadose
zone, and essentially just the diffusion coefficient was I think the
only thing, and maybe some sorption of it was retarding. But, he seemed
to have some incredibly long travel times under those extremely
conservative assumptions.

Now, when you look at the fact that we\'ve found chlorine 36, which is
essentially where it\'s been found essentially a 50 year travel time,
and he\'s showing travel time for technetium, a non-sorbing species like
chlorine 36 that are in the thousands of years, in fact, I think on the
order of 10,000 years for less than half of the technetium to reach the
water table seems to be a disconnect there.

I think the question there is how is DOE modeling the flow in fractures?
Are they modeling it as thin films on both sides of the fracture, or is
it rivulet flow? Now, obviously one of those assumptions is extremely
conservative, and the other one isn\'t, so the question is which model
is DOE using, and the justification for that.

Thank you.

BULLEN: Thank you, Don. Anyone else who would like to address the\--Dr.
Van Luik? Please identify yourself, and your affiliation, or you could
just be a member of the public, if you want.

VAN LUIK: I\'m Abe Van Luik, I work with the Department of Energy, and I
have a part-time job, which is to be a chairman of an international
expert group for the Nuclear Energy Agency. And, from the perspective of
that job, I\'d like to say something.

We sponsored a workshop at which I was not in attendance, so it\'s not
colored by my ideas, in Terku, Finland, to which the TRB sent two
representatives, on the role of the engineered barrier system in total
system performance assessment, and something that Marty Mifflin said
reminded me of this. I would recommend that the Board read the report
from that meeting.

In that report, there\'s a reflection of the maturing of the
international view of geologic disposal, and a recommendation that one
should pursue engineered containment for as long as practicable, and
that after it fails, and it will fail, it\'s inevitable, that then the
releases should not be harmful to human beings or the environment. And,
I think if you look at our EIS and other long-term looks, applying
ICRP-72, updating the model, we pretty much follow that ballpark, and so
I feel pretty good about the fact that we do, in the mature view of
geologic disposal meet what the international community thinks it\'s all
about.

That\'s all I wanted to say.

BULLEN: Thank you, Abe. Dr. Parizek is raising his hand, and I know that
I only have four minutes left, because I want to be on time like my
colleague this morning.

PARIZEK: I\'m the Chairman. I have one quick point.

BULLEN: Dr. Parizek.

PARIZEK: Terry Fisk brought up a point about, you know, the possibility
of drilling in some critical location. I only raise that appeal in the
event it\'s necessary. Right away, there are drillhole possibilities in
the Echo Canyon area on the other side, and if those holes are drilled,
then maybe there\'s no need for anything else to go into some sensitive
area. On the other hand, those holes may not solve the problem, in which
case, that would be the example of when you might want to go into this
very protected sort of area.

But, I appreciate his offer that there could be some reasons why we
could mount some recommendations that this be allowed, because of this
unique problem. So, we\'ll wait and see maybe what happens with the
other drilling program, unless you meant help get the drilling program
started. That\'s a different problem than saying where they start.

BULLEN: If you want to speak, please come to the microphone.

FISK: Well, we\'ve been working with Inyo County and the BLM on
permitting the existing wells that are planned. And, so, Echo Canyon
well within the park is part of that effort, as is one that was drilled
last April on the alluvial fan above the Furnace Creek area. We\'ve also
worked with Inyo County on access and permitting to BLM lands
immediately east of the park in the Amargosa Valley as far as it\'s a
BLM decision, but we\'ve helped out with some of the coordination, if
you will, and information on that.

Now, if we have to get into the area where the dam is, which is in the
heart of the Funeral Mountains, then it becomes logistically difficult.
It\'s hard to get a four wheel drive rig in there in some areas, and
there are people, different points of view, naturally, within the park
right now, the superintendent is very focused on water resource issues,
both locally and regionally. There are other people within the park who
believe it\'s blaspheme to bring a drill rig into an area, even a
non-wilderness area, if we go into the Funerals, then we\'re looking at
botanical, archeological, biological surveys, and the whole gamut of
issues. So, it just makes it more complex.

But, we may find what we need and hopefully, we\'ll know that answer
within\--you know, drilling was supposed to start last fall, October,
November, and now with Inyo County\'s contractual difficulties, shall we
say, it\'s hard to say, it will be the heart of summer probably, and
they\'ll want ice chests out there and fans, and so on.

BULLEN: Thank you very much. Seeing no other comments, and now I have a
question, a point of order. We will declare the open forum closed. But,
since I have the list of public commenters, do you want me to do it, Mr.
Chairman, or will you? Okay. Mr. Chairman, I will continue.

We only have one public commenter who would like to speak, and she very
graciously deferred from this morning, Judy Treichel, would you please
come forward, and choose your microphone.

TREICHEL: I don\'t need the list. I need the last one.

I totally disagree with the last question on there. I think it
shouldn\'t be on there, and I think it\'s inappropriate. How much could
the technical basis be improved by 2010? Well, throughout this program,
we\'ve had just in time engineering, we\'ve had just in time science,
and talking about just in time, you know, the magic year 2010 is when
the trucks, trains, barges, and whatever, are supposed to be pulling up
at the door of Yucca Mountain. So, I would say that\'s waiting awfully
late.

And, I think if there needed to be an improved technical basis, that
probably the Board\'s letter at the time of site recommendation should
have been a little tougher. I know we\'ve been through this, and that\'s
water over the dam. But, if the Board is asked by Congress or the NRC or
anybody, when it comes down to DOE\'s license application, what do you
think, maybe you should say well, we think maybe the technical basis
should be improved, and perhaps that should happen not before 2010, but
before any license application is accepted. So, I needed to get that
said.

I found that in the various meetings that I\'ve been to, and Lord knows
that I live at meetings, that in this one, there was very little
importance given to, or attention to climate change. It was mentioned a
lot. It was talked about a lot. But, you\'ve got studies that have just
come out from the Pentagon and from a big one done in the UK, and these
are not alarmist organizations by any means, and they all have their own
agenda, but they find climate change to be very dangerous, to be a big
deal, and to be coming very quickly. I think the Pentagon study is
talking about within the next few decades.

And, my question would be if they\'re right, if it\'s going to be a big
change, if it\'s going to happen very soon, what does that do, how does
that change everything that goes on out from there? What DOE did was to
go back a few hundred thousand years, see what happened, and then flip
the chart over and use that going forward. But, it would seem to me if
there\'s going to be some dramatic change that\'s unexpected and has not
happened before, that it might affect everything coming after that.

I always get up here with laundry lists, so I don\'t have any segues. I
just go down the list. In the discussion of Pena Blanca, I think that\'s
interesting because it\'s always brought up as being an analog, and it
may be when you\'re tapping on the rocks and when you\'re looking at how
the materials work out there and what the temperature and the setting
and so forth, but from the public perspective, it\'s not an analog. The
comment was made that it might be hard to know where the, since it\'s in
a uranium mining zone, it might be hard to know where the pollution in
the groundwater came from, because it could have come from one of the
other mines, or the other places where there\'s uranium.

Well, that\'s not the case in Amargosa Valley. Amargosa Valley isn\'t a
uranium mining district. It\'s a dairy and farming and residential
district. So, we\'re going to know where the pollution came from there,
and you\'ve got clean water now. I don\'t know if you have clean water
at Pena Blanca. I don\'t know if anybody else shares the water with that
site. But, I think I would like to know, and I\'m sure that the people
in Amargosa Valley would like to know.

There\'s been a lot of talk about Dr. Bredehoeft\'s presentation. I was
so grateful for that presentation. It was a real breath of fresh air,
and I told Priscilla I think that if I had any say over what the Board
does, I would include Dr. Bredehoeft in every session that you have. He
was asked how his information would feed back into what the project
does. Well, once again, going back to where the time table and the
sacred schedule is that DOE operates off of, I don\'t think it does feed
back in. The site has been recommended, and they\'re in a race to get a
license application in. I\'m sure that some of the data, or a lot of the
data, is probably frozen. They talk about work that they\'ve got coming
up, but if they\'re going to get a license application in and have the
licensing support network all full of their 40 million pieces of data by
June, it\'s probably not going to get back in there.

So, the only place where I disagreed with Dr. Bredehoeft was when he
said what\'s the rush to closure. And, my question would be what\'s the
rush to opening. But, of course, I\'ve been asking that for a long time.

In the area of model validation, where I have absolutely no training,
but I listened to the discussion, and there was sort of the
philosophical talk about validating models and proving models. I guess I
agree that you don\'t prove the model is right. What you find out is
that it\'s not wrong yet, and when you run it, you can have confidence
building, and you can feel good that you\'re not wrong yet, you\'re
still right, but not that you\'ve got everything right completely.

So, I know that in one of the talks, the statement was made that we
still have conceptual uncertainty, and I suppose that goes back to that
statement right there, and that issues need to be pursued. If that\'s
the case, they\'re not ready to apply for a license. And, not everything
fits into performance confirmation. I\'m sure that the performance
confirmation superman is going to fly in to save the day, and everything
will go in that basket.

There\'s a whole lot of things being thrown into the science and
technology basket that were never supposed to be there. This thing has
changed 180 degrees from when Bob Budnitz stood at one of these podiums
and told us what it was about. And, it\'s just going to blend right in
to the rest of the just in time science, and that\'s not what it\'s
there for.

And, I guess, last, I would like very much to thank DOE for refusing to
participate in this last session. That was wonderful. It opened up the
microphone to a whole lot of things that we would have rather heard. So,
I\'m very grateful for that, and thank you.

BULLEN: Thank you, Ms. Treichel. Are there comments from anyone else in
the audience? Seeing none, I guess I would just like to reiterate our
Panel chairman\'s thanks to both the staff, and to all the presenters
and all the participants in today\'s meeting, and yesterday\'s meeting.
We always get a great deal of information when we come to Nevada for
these meeting. And, I think we are adjourned until May 18th, in
Washington, D.C. Is that right, Mr. Executive Chairman? What\'s the date
of that meeting? Okay, the third week in May, Washington, D.C.

Thank you very much.

(Whereupon, the meeting was adjourned.)