United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada, OK 74820
Research and Development
EPA/600/S2-90/002 May 1990
x°/EPA Project Summary
A New Approach and
Methodologies for
Characterizing the
Hydrogeologic Properties of
Aquifers
F. J. Molz, O. Guven, and J. G. Melville
In the authors' opinion, the ability
of hydrologists to perform field
measurements of aquifer hydraulic
properties must be enhanced if we
are to improve significantly our
capacity to solve ground water
contamination problems at Superfund
and other sites. Therefore, the
primary purpose of this report is to
provide motivation and new
methodology for measuring K(z), the
distribution of horizontal hydraulic
conductivity in the vertical direction
in the vicinity of a test well.
Measurements in nearby wells can
then be used to build up three-
dimensional distributions. For
completeness, and to enhance the
usefulness of this report as a field
manual, existing methodology for the
measurement of effective porosity,
vertical hydraulic conductivity,
storativity and hydraulic head, are
presented also. It is argued that
dispersion-dominated models,
particularly two-dimensional,
vertically, averaged (areal) models,
have been pushed about as far as
they can go, and that two-
dimensional vertical profile or fully
three-dimensional advection-
dominated transport models are
necessary if we are to increase
significantly our ability to understand
and predict contaminant transport,
reaction, and degradation in the field.
Such models require the measure-
ment of hydraulic conductivity distri-
butions, K(z), rather than vertically
averaged values in the form of
transmissivities.
Three devices for measuring K(z)
distributions (the impeller flowmeter,
the heatpulse flowmeter, and a multi-
level slug test apparatus) are
described in detail, along with
application and data reduction
procedures. Results of the various
methods are compared with each
other and with the results of tracer
studies performed previously. The
flowmeter approach emerged as the
best candidate for routine K(z)
measurements. Impeller meters are
now available commercially, and the
more sensitive flowmeters (heat
pulse and electromagnetic devices)
are expected to be available in the
near future.
Three-dimensional transport
models tend to be advection-
dominated rather than dispersion-
dominated, and most of the standard
finite-difference and finite-element
algorithms produce excessive
amounts of numerical dispersion
when applied to advection-dominated
models. Therefore this report closes
by providing an introductory review
of some newer numerical methods
that produce a minimum of numerical
dispersion by tracking the flow.
This Project Summary was
developed by EPA's Robert S. Kerr
-------
Environmental Research Laboratory,
Ada, OK, to announce key findings of
the research project that is fully
documented in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
The present writers are of the opinion
that field measurement capability must
increase if we are to improve significantly
our ability to handle ground water
contamination problems associated with
Superfund and other sites. To this end,
the single most important parameter
concerning contaminant migration is the
hydraulic conductivity distribution. If one
can't predict where the water goes, how
can one expect to predict the movement
of a contaminant that is carried by the
water? Most conventional flow analyses
are based on fully-penetrating pumping
tests to get a transmissivity field and
large longitudinal dispersion coefficients
to account for contaminant spreading in
the direction of flow. We call such models
dispersion-dominated. In the authors'
opinion, the time has arrived to develop
and apply aquifer tests for determining
the horizontal hydraulic conductivity as a
function of vertical position (K(z)) within a
well or borehole. When this is done at a
number of locations in the horizontal
plane, the resulting data can serve as a
basis for developing two-dimensional
vertical cross-section, quasi three-
dimensional or fully three-dimensional
flow and transport models that do not
require large, scale-dependent, dis-
persion coefficients.
Shown in Figure 1 are dimensionless
K(z) distributions obtained at four
different scales of measurement in a
single well using an impeller meter (Molz
et al., 1989a). It is apparent that as the
measurement interval varies from 10 ft
(3.05 m) to 1 ft (0.305 m), the apparent
variability of the hydraulic conductivity
increases. This is the type of information
that is lost when fully-penetrating
pumping tests are used to obtain
vertically-averaged hydraulic conduct-
ivities.
There are several techniques for
making vertically-distributed measure-
ments, including tracer tests, flowmeter
tests, dilution tests and multi-level slug
tests, that are described in this report.
Such measurements should serve as the
basis for an improved understanding and
conceptualization of subsurface transport
pathways, and may also allow the
application of a new generation of
contaminant transport models that are
advection-dominated and largely free of
the problems associated with large,
scale.dependent, dispersion coefficients.
All of this taken together constitutes what
the authors are advocating as the new
approach to characterizing the
hydrogeologic properties of aquifers.
Selected Methodology
After studying a number of
methodologies for measuring K(z)
distributions, two techniques, the
flowmeter method and the multi-level
slug test, emerged as the most practical
methodologies for obtaining K(z)
information, and were, therefore, studied
in detail. Of the two, the flowmeter was
more responsive, less sensitive to near-
well disturbances due to drilling, and
easier to apply. As illustrated in Figure 2,
a flowmeter test may be viewed as a
natural generalization of a standard fully
penetrating pumping test. In the latter
application, only the steady pumping
rate, QP, is measured, whereas the flow
rate distribution along the borehole or
well screen, Q(z), as well as QP is
recorded during a flowmeter test.
Various types of flowmeters based on
heat pulse or impeller technology have
been devised for measuring Q(z), and a
few groundwater applications have been
described in the literature (Hess, 1986;
Morin et al., 1988a; Molz et al., 1989a,b).
The most low-flow-sensitive types of
meters are based on heat.pulse,
electromagnetic, or tracer-release
technology (Hess, 1986), but to the
authors' knowledge such instruments are
not presently available commercially,
although several are nearing commercial
availability. Impeller meters (commonly
called spinners) have been used for
several decades in the petroleum
industry, and a few such instruments
suitable for groundwater applications are
now available for purchase (Further
information available upon request). A
meter of this type was applied at the
Mobile site to produce the kind of
hydraulic conductivity data shown in
Figure 1.
Impeller Meter Tests
Once the necessary equipment is
obtained, impeller meter tests can be a
relatively quick and convenient method
for obtaining information about the
vertical variation of horizontal hydraulic
conductivity in an aquifer. The idea and
methodology behind the impeller meter
test are illustrated in Figure 2. One first
runs a caliper log to ascertain that the
screen diameter is known and constant. If
it is not constant, the variations must be
taken into account when calculating
discharge. A small pump is placed ir
well and operated at a constant flow ra
QP. After pseudo steady-state behavior
obtained, the flowmeter, which wh
calibrated measures vertical flow witl
the screen, is lowered to near the bott<
of the well, and a measurement
discharge rate is obtained in terms
impeller-generated electrical pulses o\
a selected period of time. The meter
then raised a few feet, another readi
taken, raised another few feet-and so <
As illustrated in the lower portion
Figure 2, the result is a series of d;
points giving vertical discharge, Q, witl
the well screen as a function of vertii
position z. Just above the top of t
screen the meter reading should be eqi
to QP, the steady pumping rate that
measured independently on the surfa
with a water meter. The procedure m
be repeated several times to ascerti
that readings are stable.
While Figure 2 applies explicitly to
confined aquifer, which was the type
aquifer studied at the Mobile si
application to an unconfined aquifer
similar. Most impeller meters are capal
of measuring upward or downward flc
so if the selected pumping rate, C
causes excessive drawdown, one c
employ an injection procedure as
alternative. In either case, there will
unavoidable errors near the water tal
due to the deviation from horizontal flc
It is desirable in unconfined aquifers
keep QP as small as possible consist!
with the stall velocity of the meter. Th
more sensitive meters will have
advantage.
The basic analysis procedure 1
flowmeter data is quite straightforwa
One assumes that the aquifer
composed of a series of n horizon
layers and takes the difference betwe
two successive meter readings, whi
yields the net flow, AQ, entering t
screen segment between the elevatic
where the readings were taken, which
assumed to bound layer i,(i = 1,2
One then employs the Cooper.Jac
(1946) formula for horizontal flow to a w
or an alternative procedure to obtain K
values.
Heat-Pulse Flowmeter Tests
Application of impeller met
technology will be limited at many sil
due to the presence of low permeabi
materials that will preclude the pumpi
of test wells at a rate sufficient to open
an impeller meter. Another type
flowmeter that is in the prototype sta<
the heat.pulse flowmeter, can be used
an alternative to an impeller meter
-------
Well EB Impeller Meter
130
130
140
150
170
780
790
200
0.0
I l l
(5' INTERVAL) -
130
140
150
£;760
N 770
780
790
2.0
4.0
6.0
200
1 l I i
(70' INTERVAL) -
I
K/K
0.0
2.0 4.0
K/K
6.0
Figure 1, Dimensionless horizontal hydraulic conductivity distributions based on
impeller meter readings taken at the various measurement intervals indicated
on the figure.
Pump
Cap
CO = Discharge
Rate)
Borehole Flow
Meter
Elevation =Z
To Logger (Q)
j-Land Surface
Casing
Scree/?
Data
Figure 2. Apparatus and geometry
associated with a borehole
flowmeter test.
virtually any application, and it has the
advantage of greater sensitivity. Spinner
flowmeters measure a minimum velocity
ranging from about 3 to 10 ft/min (1 to 3
m/min), which limits their usefulness in
many boreholes having slower water
movement. Flow volumes of as much as
4 gal/min (15 L7min) may go undetected
in a 4-in (10 cm) diameter borehole when
flow is measured with a spinner
flowmeter, and much larger volumes may
go undetected in larger diameter holes.
Heat-pulse flowmeters are particularly
useful for application to fractured rock
aquifers where flows are often small and
contaminant transport pathways difficult
to visualize. Such meters may be used to
locate productive fracture zones and to
characterize apparent hydraulic
conductivity distributions.
The urgent need for a reliable,
slow.velocity flowmeter prompted the
U.S. Geological Survey (USGS) to
develop a small-diameter, sensitive,
thermal flowmeter. This meter has
interchangeable flow-sensors, 1.63 and
2.5 in. (4.1 and 6.4 cm) in diameters, and
has flow sensitivity from 0.1 to 20 ft/min
(0.03 to 6.1 m/min) in boreholes with
diameters that range from 2 to 5 in. (5 to
12.5 cm). Vertical discharge in a borehole
is measured with the thermal flowmeter
by noting the time-of-travel of the heat
pulse and determining water volume flow
from calibration charts developed in the
laboratory using a tube with a diameter
similar to that of the borehole under
investigation (Hess, 1986).
The basic measurement principle of
the USGS meter is to create a thin
horizontal disc of heated water within the
well screen at a known time and a known
distance from two thermocouple heat
sensors, one above and one below the
heating element. One then assumes that
the heat moves with the upward or
downward water flow and records the
time required for the temperature peak to
arrive at one of the heat sensors. The
apparent velocity is then given by the
-------
known travel distance divided by the
recorded travel time. Thermal buoyancy
effects are eliminated by raising the
water temperature by only a small
fraction of a centigrade degree. The
geometry associated with the flowmeter
is shown in Figure 3.
Feet Meters
•1.0
3.0
•2.5
2.0
•1.5
1.0
•0.5
0.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
•0.2
•0.1
L0.0
Electronic
Section
ZFlow Sensor
%with Inflated
% Packer
Valve
8ox
Packer
Pump
Figure 3. The U.S. Geological Survey's
thermal flowmeter with inflated
flow-concentrating packer (modified
from Hess, 1988).
The USGS heat-pulse meter has been
applied to the granular aquifer at the
Mobile site and to several fracture flow
systems. In the present report the
authors describe applications to fractured
dolomite in northeastern Illinois, fractured
gneiss in southeastern New York, and a
granitic fracture zone on the Canadian
shield in Manitoba. In these applications,
supplemental information was obtained
from acoustic-televiewer logs, tem-
perature logs, and caliper logs.
Information similar to that shown in
Figure 4 was obtained. The case studies
illustrate potential application of the
thermal flowmeter in the interpretation of
slow flow in fractured aquifers. The
relative ease and simplicity of thermal-
flowmeter measurements permits
reconnaissance of naturally occurring
flows priors to hydraulic testing, and
identification of transient pumping effects,
which may occur during logging. In
making thermal flowmeter
measurements, one needs to take
advantage of those flows that occur under
natural hydraulic-head conditions as well
as the flows that are induced by pumping
or injection. However, thermal-flowmeter
measurements interfere with attempts to
control borehole conditions during
testing, because the flowmeter and wire-
line prevent isolation of individual zones
with packers. In spite of this limitation,
the simplicity and rapidity of thermal-
flowmeter measurements constitute a
valuable means by which to eliminate
many possible fracture interconnections
and identify contaminant plume pathways
during planning for much more time
consuming packer and solute studies.
The thermal flowmeter is especially
useful at sites similar to the site in
northeastern Illinois, where boreholes are
intersected by permeable horizontal
fractures or bedding planes. Under these
conditions, naturally occurring hydraulic-
head differences between individual
fracture zones are decreased greatly by
the presence of open boreholes at the
study site. These hydraulic-head
differences could only have been studied
by the expensive and time consuming
process of closing off all connections
between fracture zones in all of the
boreholes with packers. The simple and
direct measurements of vertical flows
being caused by these hydraulic-head
differences obtained with the thermal
flowmeter provided information pertaining
to the relative size and vertical extent of
naturally occurring hydraulic-head
differences in a few hours of
measurements. Additional improvement
of the thermal-flowmeter/packer system
and refinement of techniques for
flowmeter interpretation may decrease
greatly the time and effort required to
characterize fractured-rock aquifers by
means of conventional hydraulic testing.
While the case studies described in the
present report did not all involve
contaminated groundwater, the potential
application to plume migration problems
and sampling well screen locating is
obvious. The relationship of flowmeter
measurements to more standard tests
such as caliper and televiewer logs
indicated also. Hopefully, therm
flowmeters and other sensitive devic<
such as the electromagnetic flowmet
being developed by the Tennesse
Valley Authority (Young and Waldro
1989) will be available commercially
the near future.
Multilevel Slug Tests
The flowmeter testing procedure
generally superior to the multilevel sli
test approach, because the latti
procedure depends on one's ability
isolate hydraulically a portion of the te
aquifer using a straddle packer. Howeve
if reasonable isolation can be achieve
which was the case at the Mobile te
site, then the multi-level slug test is
viable procedure for measuring K(z). /
equipment needed for such testing
available commercially, and the te
procedure has the added advantage '
not requiring any water to be injected in
or withdrawn from the test well if a wati
displacement technique is used to caus
a sudden head change.
The testing apparatus used in th
applications reported herein is illustrate
schematically in Figure 5 for the aquifi
geometry at the Mobile site (Melville <
a!., 1989). Two inflatable packei
separated by a length of perforate*
galvanized steel pipe comprised th
straddle packer assembly. Aquifer te:
length as defined by the straddle pack*
was L = 3.63 ft (1.1 m). A larger packe
referred to as the reservoir packer, viz
attached to the straddle packer with 2
(2.54 cm) Triloc PVC pipe, creating a un
of fixed length of approximately 100
(30.5 m) which could be moved with th
attached cable to desired positions in th
well. When inflated, the straddle pack(
isolated the desired test region of th
aquifer and the reservoir packer isolate
a reservoir in the 6" (15.2 cm) casin
above the multilevel slug test unit an
below the potentiometric surface of th
confined aquifer.
In a typical test, water was displaced i
the reservoir above the packer. The hea
increase then induced a flow dow
through the central core of the reserve
packer and down the Triloc pipe to th
straddle packer assembly. In th
assembly, water flowed from th
perforated pipe, through the slotted we
screen, and into the test region of th
aquifer.
The multilevel unit described was use
for slug tests by inserting the plunge
displacing a volume of water in th
reservoir and then recording the dept
variation, y = y(t), relative to the initi;
-------
South
700
800
URL 15
S
O)
"8 900
.c
£
& 1000
1100
Outflow
Projections of
Fractures
0.25 Umin
0.07 gpm
URL14
North
0.25 Umin
0.07 gpm
Fracture
/Zone
200
- 250
I
1
s
•3
1
I
Figure 4. Distribution of vertical flow measured with the heat-pulse ftowmeter in boreholes
URL14 and URL15 in southeastern Manitoba superimposed on the projection of
fracture planes identified using the acoustic televiewer.
Depth _
Recorder Cable
Figures. Schematic diagram of the
apparatus for performing a multi-
level slug test.
potentiometric surface (falling head test).
Plunger withdrawal was used to generate
a rising head test. Head measurements
were made with a manually operated
digital recorder (Level Head model LH10,
with a 10 psig pressure transducer, In
Situ, Inc.).
Three methods of analysis have been
pplied to the collected slug test data. In
the first and second methods, it is
assumed that the flow from the test
section is horizontal and radially
symmetric about the axis of the well. In
the first method the quasi-steady state
assumption is made. In the second, a
transient analysis is applied. In the third
analysis, also quasi-steady state, the
possibility of vertical flow and anisotropy
are considered using curves generated
by a finite element model.
Typical results of a series of tests at
different elevations are shown for well E6
in Figure 6. The data shown are from
plunger insertion tests where a sudden
reservoir depth increase to approximately
y°=3ft. was imposed. The depth
variation, y = y(t), which is nearly an
exponential decay, is a result of flow into
the aquifer test section adjacent to the
straddle packer. The different slopes of
the straight line approximations (least
squares fits) are due to the variability of
the hydraulic conductivity in the aquifer
at the different test section elevations.
Tests repeated at a given elevation were
generally reproducible, with the
maximum difference in slopes of the
straight line fits to the data being less
than 11%. From this data it is easy to
calculate hydraulic conductivity distri-
butions as described in the report.
10
100 200
Time (sec)
•*• iog(y)=-o.0280t+0.47
•*- log(y)=-o.oo20t+0.50
*log(y) =
»log(y) =
^log(y) =
-log(y)-
2
Z
Z
Z
-0.00411 + 0.51 Z
-0.0034t + 0.49 Z
-0.00261 + 0.47 Z
-0.00461 + 0.48 Z
-0.00531 + 0.48 Z
-0.0071 +-0.47 Z
-0.0092t + 0.50 Z--
300
= 11.2 ft
-17.2 ft
=23.2 ft
• 5.2ft
= 29.2 ft
--35.2 ft
•-41.2 ft
-•47.2 ft
••53.2 ft
59.2 ft
65.2ft
Figure 6. Multilevel slug test data from well
E6, B=Log
-------
Modeling of Advection-
Dominated Flows
There are a variety of ways in which
vertically-distributed hydraulic conduct-
ivity distributions can be used to
understand and assess problems
involving contaminated ground water. A
significant amount of insight will be
obtained simply by observing and
discussing the implications of such
information on patterns of contaminant
migration. However, use of the vertically-
distributed data in three-dimensional
mathematical models will be a common
procedure for developing quantitative
assessments of a variety of possible
activities such as evaluation of site
remediation plans. Thus it is worthwhile
to devote part of this report to a
discussion of the relationship between
vertically-distributed hydraulic conduct-
ivity data and mathematical modeling
(Giivenetal., 1989).
As pointed out previously, once one
moves from the use of vertically-
averaged aquifer properties in two-
dimensional mathematical models to the
use of vertically-distributed aquifer
properties in three-dimensional models,
the nature of the physical process
represented by the model changes
dramatically. In many situations, the
model changes from one being largely
dominated by dispersion (low Peclet
number flows) to one largely dominated
by advection (high Peclet number flows).
Unfortunately, most of the standard finite-
difference and finite-element algorithms
for solving mathematical models do not
work well when applied to advection-
dominated flows, especially those that
involve chemical or microbial reactions.
The necessary evolution from dispersion-
dominated to advection-dominated
numerical algorithms for solving the flow
and transport equations is far from trivial,
so it is important to call attention to some
of the newer numerical methods,
particularly those that produce a
minimum of numerical dispersion when
used to solve the transport equation.
A complete numerical analysis of
contaminant migration in the subsurface
usually involves solution of the ground
water flow equation and the transport
(advection/dispersion) equation. The
latter equation is the more complicated
due primarily to the existence of the
advective transport term which gives the
transport equation a hyperbolic character
and makes its solution subject to
numerical dispersion. In general, the
techniques for solving such an equation
can be grouped into three classes;
namely, Eulerian, Lagrangian, and
Eulerian-Lagrangian methods. Eulerian
methods are more suited to dispersion-
dominated systems while Lagrangian
methods are most suited to advection-
dominated systems. Eulerian-Lagrangian
methods have been introduced to deal
efficiently and accurately with situations
in which both advection and dispersion
are important.
The Eulerian methods are based on the
discretization of the transport equation on
a numerical solution grid that is fixed in
space, and all of the terms of the
equation, including the advective
transport term, are discretized together
and the resulting algebraic equations are
solved simultaneously in one solution
step. As discussed by Cady and Neuman
(1987), while Eulerian methods are fairly
straightforward and generally perform
well when dispersion dominates the
problem and the concentration
distribution is relatively smooth, they are
usually constrained to small local grid
Peclet numbers.
Methods which are based on solutions
of the transport equation on a moving
grid, or grids, defined by the advection
field, or methods which do not rely on a
direct solution of the Eulerian transport
equation but which are based on an
analysis of the transport, deformation and
transformation of identified material
volumes, surfaces, lines or particles by
tracking their motion in the flow field are
generally called Lagrangian methods
(Cady and Neuman, 1987). In the present
report, we reserve this term only for
methods which are based on tracking
alone and will consider the moving-grid
methods which have been called
Lagrangian before by some authors
simply as special cases of the Eulerian-
Lagrangian methods.
Reviews of Eulerian-Lagrangian
methods (ELM) have also been
presented recently by Cady and Neuman
(1987). These methods combine the
advantageous aspects of the Lagrangian
and the Eulerian methods by treating the
advective transport using a Lagrangian
approach and the dispersive transport
and chemical reactions using an Eulerian
approach. According to how the
advective transport is taken into account,
these methods can be generally grouped
into three classes; one class makes use
of particle tracking and relates the
concentration at a grid node to the solute
mass associated with each particle and
the particle density around that node,
while the second class treats
concentration directly as a primary
variable throughout the calculations
without resorting to the use of a
particles, and the third class consists
models in which the first and seco
approaches are used together in
adaptive manner depending on tl
steepness of the concentration gradient
It may be useful to point out th
Eulerian-Lagrangian methods have be
developed extensively for the numeric
modeling of complex three-dimensior
industrial and environmental flows and I
the solution of various fluid mechani
problems particularly over the la
decade (Oran and Boris, 1987). The
methods are now becoming popular al
in the area of subsurface contamina
migration modeling.
Availability of Computer Code!
Several well documented comput
codes for three-dimensional flow ai
solute transport modeling as well ,
parameter identification and uncertain
analysis are available in the publ
domain. These codes have bee
developed by universities, varioi
government agencies and governme
supported laboratories. There are al
several proprietary codes developed I
private consulting firms and resean
organizations such as the Electric Pow
Research Institute. Many of these cod
have been listed in the rece
monographs by Javandel et al. (198
and van der Heijde et al. (1985). In tl
regard, the International Ground Wat
Modeling Center (IGWMC) serves as ,
information, education, and resean
center for groundwater modeling wi
offices in Indianapolis, Indiana (IGWM
Holcomb Research Institute, Butl
University, 4600 Sunset Avenu
Indianapolis, Indiana 46208) and Del
the Netherlands. IGWMC operates as
clearinghouse for groundwater modelii
codes and organizes an annual series
short courses on the use of varioi
codes. Similar specialized short coursi
are also organized by various universitii
as well as professional organizatioi
such as the National Water We
Association (NWWA, 6375 Riverside D
Dublin, Ohio 43017). NWWA al:
maintains the Ground Water On Lii
computer data base for publications
the ground water area. Th
aforementioned references ar
organizations may be consulted for tl
availability of various modeling codes.
Supplemental Information
This report is devoted mainly to
presentation of the information ai
experience gained from six years of fie
experimental and theoretical studies I
-------
Auburn University that was funded by the
U.S. Environmental Protection Agency
through the Robert S. Kerr Laboratory. In
one way or another, most of this work
dealt with the understanding and
measurement of hydraulic conductivity
distributions in the field, with all
measurements made in the saturated
zone. However, the title of the present
report, "A New Approach and
Methodologies for Characterizing the
Hydrogeologic Properties of Aquifers,"
implies more than the measurement of
horizontal hydraulic conductivity as a
function of vertical position in a granular
aquifer. The additional information,
including methodology for measuring
specific storage, porosity, hydraulic head,
and hydraulic conductivity in the vertical
direction, was kindly supplied by a
Colleague at the Lawrence Berkeley
Laboratory and is included in the report
in two separate chapters.
Most individuals attempting to deal with
subsurface contamination problems in the
field are well aware that more information
is needed than that resulting from the
measurement of hydrogeologic
properties as they are defined herein.
Measurement of chemical and
biochemical subsurface properties, input
from geologists, geophysicists, biologists
and other scientists, measurement of
subsurface geometry, and information
concerning the interplay of field
measurements and regulation are all
important, but beyond the scope of this
report. In order to compensate for this
shortcoming, a national conference
entitled "New Field Techniques for
Quantifying the Physical and Chemical
Properties of Heterogeneous Aquifers"
was convened in Dallas, Texas on March
20-23, 1989. Similar to this report, the
conference was motivated by the need to
enhance field measurement capabilities
if, as a Nation, we are to solve the many
site-specific problems being addressed
by the Superfund and other programs.
The meeting provided a much needed
forum for professionals from government
regulatory agencies, universities, and
private industry to discuss, describe or
display the best and most applicable
techniques or equipment for measuring
aquifer properties that have an important
influence on contaminant migration. The
conference featured a broad spectrum of
invited and submitted papers and
displays dealing with the most important
topics facing ground water scientists,
engineers and consultants in this field of
inquiry. Approximately 50 papers were
presented and the 883 page proceedings
is available from the Water Resources
Research Institute. 202 Hargis Hall,
Auburn University, AL 36849 at a
moderate cost. The proceedings is
intended to serve as a broad-based
supplement to this report.
Given the current level of
understanding concerning contaminant
migration in porous media, it was
necessary for the authors of this report,
and also for the participants in the
aforementioned conference, to attempt to
identify practical and useful measurement
techniques and equipment while
recognizing the fact that we are working
within a framework of basic
understanding that is far from perfect.
This is a classical example of a situation
that requires innovative engineering
solutions. Within this context, it is hoped
that the work described in the present
report will serve as part of the basis for
the "next step" in field measurements
that must be taken if we are to improve
significantly our ability to characterize,
evaluate and reclaim contaminated
aquifers.
References
Cady, R., and S.P. Neuman. 1987.
Advection-dispersion with adaptive
Eulerian-Lagrangian finite elements. In:
Advances in Transport Phenomena in
Porous Media, edited by J. Bear and
M.Y. Corapcioglu. NATO ASI Series E:
Applied Sciences, No. 128, Dordrecht,
The Netherlands: Martinus Nijhoff
Publishers.
Guven, 0., F.J. Molz, and J.G. Melville.
1989. Modeling migration of
contaminants in the subsurface
environment. In: Hazard Assessment
of Chemicals. 7, 203-282, edited by J.
Saxena, Hemisphere Publishing Corp.,
Washington, D.C.
Hess, A.E. 1986. Identifying hydraulically
conductive fractures with a slow-
velocity borehole flowmeter. Canadian
Geotechnical Journal, 23,69-78.
Javandel, J., C. Doughty, and C.F. Tsang.
1984. Groundwater Transport:
Handbook of Mathematical Models,
American Geophysical Union,
Washington, D.C., 228 pp.
Melville, J.G., F.J. Molz, 0. Guven and
M.A. Widdowson. 1989. Multi-level
slug tests with comparisons to tracer
data. Ground Water, submitted for
publication.
Molz, F.J., R.H. Morin, A.E. Hess, J.G.
Melville, and 0. Guven. 1989a. The
impeller meter for measuring aquifer
permeability variations: evaluation and
comparison with other tests. Water
Resources Research, 25, 1677-1683.
Molz, F.J., 0. Guven, J.G. Melville, and
C. Cardone. 1989b. Hydraulic
conductivity measurement at different
scales and contaminant transport
modeling. In: Dynamics of Fluids in
Hierarchial Porous Media, edited by
J.H. Cushman. New York, Academic
Press, in press.
Morin, R.H., A.E. Hess, and F.L. Paillet.
1988a. Determining the distribution of
hydraulic conductivity in a fractured
limestone aquifer by simultaneous
injection and geophysical logging.
Ground Water 26, 586-595.
Oran, E.S., and J.P. Boris. 1987.
Numerical Simulation of Reactive
Flow. Elsevier, New York.
van der Heijde, P., Y. Bachmat, J.
Bredehoeft, B. Andrews, D. Holtsz,
and S. Sebastian. 1985. Groundwater
Management: The Use of Numerical
Models, 2nd ed. American
Geophysical Union, Washington, D.C.
Young, S.C., and W.R. Waldrop. 1989. An
electromagnetic borehole flowmeter
for measuring hydraulic conductivity
variability. Proceedings of the
Conference on New Field Techniques
for Quantifying the Physical and
Chemical Properties of Heterogeneous
Aquifers, March 20-23, Dallas, Texas
(available from: WRRI, Auburn
University, AL 36849).
-------
F. J. Molz, O.Guven, and J. G. Melville are with the Civil Engineering
Department, Auburn University, Alabama 36849.
Lowell E. Leach is the EPA Project Officer (see below).
The complete report, entitled "A New Approach and Methodologies for
Characterizing the Hydrogeologic Properties of Aquifers," (Order No. PB
90-187 063 ; Cost $31.00 subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-90/002
UNOFFICIAL MAIL
61)90444
tl.SJOSTAGE
s 0 .3 5
CHICAGO
------- |