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13th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
- Conference date: 20 Feb 2000 - 24 Feb 2000
- Location: Arlington, Virginia, USA
- Published: 20 February 2000
61 - 80 of 140 results
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Dielectric Permittivity Of Clay-Water Mixture: Frequency Dependency And Volumetric Mixing Model
By Birsen CananThe dielectric permittivities of Na- and Ca- montmorillonite-water mixtures were
measured with respect to frequency (0.03-300 MHz), and two different inorganic salts (NaCl,
and CaC12). For the volumetric mixing model of the clay-water mixtures, the model suggested by
Schwarz (1962) was investigated and with slight modification, this model was applied to
calculate dielectric permittiviy of clay-water mixture.
It is seen from the measured dielectric permittivity values and frequency spectra analysis
that polarization of ions in the electrical double layer plays an important role in the high values
of dielectric pemittivities of clay-water mixtures even at higher frequencies. A comparison of the
frequency response signature of these materials suggest the possibility of material identification
based on measurements made over a wide frequency bandwidth.
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A Physiochemical Interpretation Of The Cole-Cole Dielectric Model
Authors David Lesmes, John Sturrock and Kevin FryeThe Cole-Cole dielectric model has been extensively used to fit the observed broadband
electrical properties of water-saturated rocks and soils as well as many other types of ionically
conducting solids (e.g. colloid suspensions, porous glasses, and biological tissues). The Cole-
Cole model was empirically derived and consists of three fitting parameters: the dielectric
increment (AZ), a major relaxation time (TO>, and a dispersion parameter (a). In addition to these
three parameters it is common to include frequency independent terms for the low-frequency
conductivity (oslatic) and the high-frequency permittivity (cm> of the sample. Although the Cole-
Cole model has been extensively used for the interpretation of both low-frequency spectral
induced-polarization data and high frequency dielectric data, the significance of the model
parameters is still not well understood. In this paper we present a physicochemical interpretation
of the Cole-Cole dielectric model. It is shown that the Cole-Cole parameters r and a can be
related to the mean and variance of the grain size distribution and & is a weighted product of the
specific surface area and the surface charge density.
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Crosswell Seismic Reflection Imaging Of A Shallow Cobble-Andsand Aquifer: An Example From The Boise Hydrogeophysical Research Site
Authors Lee M. Liberty, William P. Clement and Michael D. KnollCrosswell seismic data contain first-arrival information for velocity inversion and reflections
for seismic stratigraphic analysis. Seismic velocity information is useful for directly comparing
to, and inverting for, physical properties such as porosity. Reflections within the data are
often under utilized, but can help map the subsurface structural architecture that often define
hydrostratigraphic bounding surfaces between sedimentary units. We have acquired numerous
crosswell data sets from the Boise Hydrogeophysical Research Site (BHRS), a shallow (less than
20 m depth) cobble-and-sand unconfined aquifer. Preliminary crosswell seismic reflection results
show meter-scale structure that can help constrain our velocity model and define seismic boundaries
that first arrival tomograms cannot provide. Both crosswell reflection and velocity information
can help constrain hydrostratigraphic parameters that may be used to model groundwater
flow.
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Tomographic Inversion Of Crosshole Radar Data: Confidence In Results
Authors William P. Clement and Michael D. KnollCrosshole radar tomography is increasingly being used to characterize the shallow subsurface
and to monitor hydrologic processes. Although tomographic inversion provides a subsurface
model, confidently interpreting the resulting image can be challenging. We conducted a simple
modeling study to better understand the capabilities and limitations of tomographic inversion. We
start with a known earth model, simulate a tomography experiment, and invert the synthetic data.
We investigate the effects of straight and curved ray approximations to wave propagation, regularization,
grid size, and starting model. We also investigate the effects of limited ray coverage
through the earth model and noise in the data. Understanding the effects of these different methods
and parameterizations will help us place confidence limits on modeled features to more accurately
reflect our knowledge of the subsurface.
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Borehole Geophysics As An Aid To Kimberlite Exploration In The Canadian Prairie Region
Authors Paul Bauman, Richard Kellett, Russ Pagulayan and Andrew HinnellThis paper examines various suites of logs from a number of kimberlite fields in the Western
Canadian Sedimentary Basin. It is observed that while the physical properties of kimberlite may
vary widely, even within a single borehole or pipe, borehole geophysical logs do effectively
distinguish kimberlite from the host rock. Ranges of physical properties, including magnetic
susceptibility and formation resistivity, can be identified and used in forward magnetic and
geoelectrical modeling. Airborne data can thus be modeled with greater confidence, while the
effectiveness of various ground based techniques can be predicted in advance of field programs.
In addition, logging programs have been useful in identifying kimberlitic material that may have
been bypassed in the drilling progam, in locating offhole bodies, and in sterilizing prospects
identified from incorrectly modeled surface magnetic data.
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Borehole Geophysical Characterization Of Hydraulic Stimulation Of Fractured Bedrock Aquifers
Authors Frederick L. Paillet and Harry HanscombChanges induced by typical hydraulic stimulation procedures were monitored in two
adjacent boreholes at a site in northeastern Maine by comparing geophysical well logs run before
and alter stimulation. Caliper and acoustic televiewer logs run before stimulation indicated a
few faint, impermeable-looking horizontal and vertical fractures, but inflow before treatment was
too weak to detect with a heat-pulse flowmeter. Caliper and televiewer logs run after stimulation
showed no significant differences compared to the pre-stimulation logs. Flow logs run after
stimulation demonstrate that inflow in both boreholes is associated with a faint horizontal
fracture on the televiewer logs near 60 m in depth, which appears no different from several other
similar fractures. A cross-borehole flow experiment confirms that the stimulated zone is a single
horizontal fracture connecting the two boreholes. These results demonstrate that the hydraulic
stimulation produced at least a IO-fold increase in well capacity from less than 0.5 to more than
5.0 liters per minute. The results also agree with previous studies where fractures affected by
stimulation: 1) were present before treatment; 2) showed no obvious changes in the immediate
vicinity of the borehole after stimulation; and 3) experienced a 10 to 20 fold increase in
permeability attributed to the treatment.
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Ground Penetrating Radar Survey Of Interstate 70 Across Missouri
Authors Steve Cardimona, Brent Willeford, Doyle Webb, Todd Lippincott, John Wenzlick and Neil AndersonThis study summarizes a ground penetrating radar survey along Interstate 70 across the state of
Missouri. Goals of this survey were threefold: 1) determine asphalt and concrete layer thickness
every tenth mile; 2) update history information related to types of pavements that make up 170
across Missouri; and 3) note regions where the radar signal appears anomalous. Goals (1) and (2)
are related and were the primary goals. Goal (3) required visually interpreting the full data set and
was done as a guide for further investigation. The result is an extensive data set allowing the user
to visualize the east and westbound pavement profiles in comparison to design history information,
view a table of surface types and anomalous regions associated with those profiles, and crossreference
this information with the radar-interpreted layer data at 0.1 mile marks in spreadsheet
form.
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Geophysical Site Characterization In Support Of Highway Expansion Project
Authors Todd Lippincott, Steve Cardimona, Neil Anderson, Shane Hickman and Tim NewtonWe performed an integrated survey using ground penetrating radar (GPR), shallow highresolution
reflection seismic and dipole-dipole electrical resistivity methods in order to
characterize a site slated for roadway development. The intent of this project was to investigate
the subsurface and determine the structure of the dolomite bedrock along a proposed expansion
area for Highway 63, near Cabool, Missouri. We acquired a total of 68 GPR profiles to cover the
area of highest interest, including a sinkhole visible at the time of the survey. Five highresolution
seismic reflection profiles and four multi-channel resistivity lines were positioned
along key GPR survey lines. The soil to weathered bedrock interface appears as high amplitude
disturbed reflections and diffractions on the GPR profiles. The seismic images contain
anomalous sections of bedrock represented by diffractions and missing or offset reflections.
Pseudo-section resistivity data indicates highly resistive regions within the subsurface that
correlate with areas of concern on both the seismic and GPR data. We ranked areas based on
whether one, two, or all three of the methods indicated anomalies. The correlation of anomalous
areas across data from all three geophysical methods provides the spatial information necessary
for further geotechnical investigation prior to construction.
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Application Of Multifocusing Seismic Processing To Gpr Data Analysis
Authors A. Berkovitch, L. Eppelbaum and U. BassonA multifocusing seismic processing (MFSP) is based on the homeomorphic imaging
theory and consists of stacking seismic data with arbitrary source-receiver distribution
according to a new local moveout correction. Three-parameter travel time representation
allows to obtain a precise approximation not only for the CMP travel time curves, but
also for the full multi-coverage travel time surfaces. In MFSP observed data are stacked
along a full travel time surface whereas in the CMP are used only hyperbolas. MFSP does
not require any knowledge of the subsurface model and produces an accurate zero offset
section, even in the cases of complicated geological structure and low relation
signal/noise. The optimal sets of parameters obtaining in MFSP (emergence angle of
normal rays and two fundamental solutions of differential equations of wavefront) play
an important role in the analysis of wavefield distribution. These parameters can be used
as initial ones for inverse problem solution and construction of velocity model. MFSP
with some modification may be applied for the ground penetrating radar data processing.
We illustrate application of MFSP technique to GPR profile aimed to map stratigraphy at
quarry “Nesher” in the Central Israel. The obtained results show that the presented
method may be effectively used together with conventional procedures.
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The Signal Of Gpr At A Hydrocarbon Contaminated Site
Authors Jamile Dehaini, Wagner Franca Aquino and Jose Milton Benetti MendesThis paper presents part of a case study of contamination by a leak in a of gasoline tank,
carried out at a gas station, in the city of Sso Paulo, Brazil. The GPR method was applied to
evaluate the quantitative behavior of the signal (velocity, spectral and amplitude analysis,
and instantaneous attributes) related to contamination. This analysis intends to establish a
more objective tool for the interpretation of contaminated areas compared with that
available in the literature. Thus, its application could be extended to provide a more reliable
diagnosis of the contaminant plume in subsurface. The field survey was performed in two
phases: before and after pumping the total free phase of the contaminant both comprised of
reflection profiling and CMP’s.
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Sub-Bottom Gpr For Mapping Lithology And Structure Of Lake Michigan Glacial Drift Deposits, Offshore Manistee, Mi
Authors Matthew VanderEide and William A. SauckThe WMU underwater GPR antenna has been applied to problems in mapping
structures and lithologies of glacially deposited sediments and younger fluvial and
lacustrine sediments in the near offshore of a part of the east-central shoreline of Lake
Michigan. Nearly 19 km of ground-penetrating radar lines have been profiled along the
reach beginning at Manistee and extending northward 7.5 km. The boat-towed bottom
sled contained a dipole antenna transmitting at about 145 MHz. Concurrent SONAR
tracks were recorded, and navigation was by differential GPS. The Lake Michigan basin
has had a complicated Pleistocene history. The rising water from a low stage 10,000
years BP have planed off and inundated a great variety of subaerial and fluvial features,
as well as deposits left by earlier glacial cycles. A large dune field was found, and using
orthogonal transects we were able to determine the strike of the slip faces, and hence the
paleo wind direction (NW to SE). Cobble and boulder tills could be recognized by the
poor radar penetration and frequent hyperbolae from individual boulders. Filled fluvial
channel-forms were found near Manistee. A sequence of at least eight layers of gently
shoreward-dipping sand beds was found. These thicken towards shore and are truncated
at the lake bottom in the offshore, updip direction, and remain an enigma. There are a
number of advantages of doing the GPR under the lake rather than onshore. At the lake
bottom, coupling is constant, topography is very smooth and predictable, and access is
unlimited. The 20 km surveyed for this project required only two (long) field days.
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Earthquake Occurrence Disclosure In Historical Environmental Site Assessments Performed In New England
More LessThe New England Seismic Network (NESN) operated by Boston College and MIT with funding
from the United State Geological Survey (USGS) has documented approximately 1000
earthquakes in the six New England states of Connecticut, Massachusetts, Rhode Island, New
Hampshire, Vermont, and Maine between late 1600’s to the 1990’s. Compared to other regions
of the United States, the apparent large number and frequency of reported earthquakes in New
England are low.
Disclosure of the potential for an earthquake to occur in New England is frequently absent in a
Historical Environmental Site Assessment (HESA) for commercial/industrial properties. Likely
reasons for this omission are the low frequency of occurrence and magnitude of earthquakes and
the public’s perspective of “there are no earthquakes in New England”. Examination of
earthquake occurrence data reported on the NESN website for the years between the late 1600’s
to 1990’s relative to the frequency and intensity of reported earthquake occurrence is evaluated
from an environmental consultant’s perspective. This information is readily accessible and
should be incorporated into HESA reports as useful information to a client even after completing
a New England HESA.
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The Electrical Resistivity - Acoustic Velocity Relationship: A Method For Constraining Porosity
Authors Wendy Wempe and Gary MavkoWe present a method for bounding the relationship between formation resistivity factor and
compressional velocity, which not only constrains possible data pairs, but also constrains
porosity. The technique involves simply combining the well-known Hashin-Shtrikman bounds
for electrical conductivity and acoustic velocity. The significance of this procedure is in it’s
potential for using relationships between formation factor and material properties in sediments
and rocks to explain velocity trends and vice versa.
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Downhole Seismic Logging Techniques In A Regional Hydrogeology Study, Oak Ridges Moraine, Southern Ontario
Authors S.E. Pullan, J.A. Hunter, A. Pugin, R.A. Burns and M.J. HintonDownhole seismic logging surveys have been carried out in plastic-cased, continuously-logged
boreholes drilled in the Oak Ridges Moraine (ORM) area in support of a regional hydrogeology study.
Compressional-wave logs were obtained using a multi-channel hydrophone array with 0.5 m detector
spacings and a surface in-hole shotgun source. These data provide detailed and accurate velocity
profiles down the hole. In this area, high velocities (>2500 m/s) are associated with the Newmarket Till,
a regionally significant aquitard. These velocities are significantly higher than those associated with
adjacent stratigraphic units, and more clearly delineate the Newmarket Till than other borehole logs
(natural gamma, conductivity or magnetic susceptibility). These data show that the Newmarket Till is
a thick (10’s of metres) unit that can be traced regionally beneath the Oak Ridges Moraine. The
downhole seismic data also provide a direct correlation between reflection events and depths which
improves the calibration and interpretation of surface seismic reflection data. Shear-wave logs have
been obtained in one ORM borehole using a compass-oriented, S-component, well-locked geophone.
In this borehole, preliminary correlations have been made between seismic velocities (both
compressional and shear) and porosity measurements obtained from the core.
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Integration Of A Seismic Reflection Survey With Traditional Geological Techniques To Site Monitoring Wells In An Unexploded Ordnance Area
Authors Melinda G. Truskowski, Mary Jane Stell and Bart HoekstraThe complex geological setting of the open burning/ open detonation (OB/OD) area of a former
demilitarization facility made conceptual hydrogeologic model development problematic. The
OB/OD area is located on the flank of a regional uplift where geologic strata transition from
nearly flat lying to dips of nearly 50 degrees. OB/OD operations as well as cutting and deposition
by an arroyo located through the center of the area have obscured the surface geology. Explosive
constituents have been detected in both the soil and ground water. A seismic reflection survey
was performed in the OB/OD area to better define the subsurface geological relationships, and
structural features within the area that could be influencing ground water flow. Since the
underlying geology strongly influences ground water occurrence and flow, a depth of
investigation exceeding 500 feet was necessary to achieve the project objectives. The seismic
source for this survey was the iVi Minibuggy vibrator, which is capable of maneuvering in the
steep and rugged terrain encountered at this site. One hundred twenty receiver channels were
recorded for this survey. To correlate the seismic reflectors to geologic horizons, two borings
were installed on one of the seismic lines. Coring and downhole logging were performed to
better characterize the geology at those points. Following interpretation of the seismic data, the
results were incorporated with traditional sources of geological data such as surface geologic
mapping and boring logs. This integrated approach provided an understanding of the site
hydrogeology to select monitoring well locations.
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Field Verification Of Monitoring Wells Sited In An Unexploded Ordnance Area Using Seismic Reflection Survey And Traditional Geological Techniques
Authors Mary Jane Stell, Robert Gregory and Melinda G. TruskowskiBase Realignment and Closure of a former munition storage and demilitarization facility initiated
the closure of a RCRA permitted open burning/ open detonation (OB/OD) area. Explosive
constituents detected in soil and ground water necessitated an assessment to define impacts to
ground water and to design a monitoring well network, required during the post-closure care
period. The complex geological setting of the OB/OD area, located on the flank of a regional
uplift where geologic strata transition from nearly flat lying to dipping up to 60 degrees westward
with numerous faults, made development of a conceptual hydrogeologic model problematic. A
seismic reflection survey was performed to better define the surface and subsurface geological
relationships, and structural features within the area that could be influencing ground water flow.
Following interpretation of the seismic data, the results were incorporated with traditional
sources of geological data to select monitoring well locations.
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Vertical Distribution Of Microbial Abundances And Apparent Resistivity At An Lnapl Spill Site
Authors D. Dale Werkema, Estella Atekwana, William Sauck, Silvia Rossbach and Joe DurisIn an attempt to better understand the anomalously high conductivities in and below free
product/residual Light Non-Aqueous Phase Liquid (LNAPL) plumes, continuous soil
samples were obtained from four locations in the Carson City Park, which is located
adjacent to the former Crystal Refinery in Carson City, MI. The samples were taken
from borings next to monitoring wells, and Vertical Resistivity Probes (VRPs). Two of
the collection sites extended off the free product plume and include one site within the
dissolved product plume and another, considered the control, located outside of known
contamination. The two remaining locations occur within the LNAPL free product
plume. Sub-samples, used for counts of cultured bacteria, were removed from the sides
of the original cores at small vertical intervals. The bacterial counts were correlated with
the bulk apparent resistivities measured in the corresponding VRPs, and with the
sediment descriptions. In general, there is an orders-of magnitude increase in bacterial
abundance at the levels where the apparent resistivity is at a minimum. The control site
gave a good indication of natural vertical and lateral background variability in the
absence of LNAPL. The results indicate that apparent resistivity measurements can
provide a window into the biogeochemical processes ongoing at LNAPL-impacted sites.
The results continue to encourage the use of resistivity as an option to monitor the natural
or enhanced bioattenuation of such sites.
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Resistivity Imaging Of A Partially Reclaimed Coal Tailings Pile
Authors Mia A. Painter, Brett Laverty, Mary W. Stoertz and Douglas H. GreenAn electrical resistivity investigation was conducted at a partially reclaimed valleyfill
coal tailings pile in southeastern Ohio to determine the tailing thickness and to evaluate
the variation within the fill material. The study concentrated on a former slurry pond at the
Flint Run site. Dipole-dipole arrays were used to generate apparent resistivity
pseudosections with a station spacing of 5 m and a maximum dipole separation (n) of 6.
The pseudosections were inverted with a least squares method to produce resistivity
images of the pile to depths of 30 m along 870 m of profile lines. Comparison of the
images to data borehole lithology and conductivity logging shows strong correlation
between the occurrence of coal tailings and acid mine drainage (AMD) saturated waste
rock (as opposed to consolidated siltstone and sandstone) and resistivity lows. The
saturated coal and waste rock appear as resistivities below 20 Rm; consolidated siltstone
and sandstone appear as resistivities above 50 Rm. The slurry dam is seen in the images as
a resistivity high and the tailings in the former slurry pond are seen to increase in thickness
and/or depth consistent with the historical drainage.
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Location And Delineation Of Subsurface Tar Contamination Using Electrical Methods
Authors Elizabeth Granger and Samuel T. PeavyElectrical resistivity and induced polarization (IP) measurements were made to explore the
variability of electrical parameters within tar-contaminated soils at the site of a former shingle
manufacturing facility on the floodplain of the Oswego River in Fulton, NY. Degradation of the
buried shingles generated diapirs of tar, which extrude onto the surface, creating self-replenishing
“tar boils” at the site. Data from offset Wenner electrical resistivity surveys conducted in December
of 1997 and 1998 were used to delineate highly resistive areas believed to be associated with the tar.
Trenching and drilling after the 1997 effort revealed tar in some of the resistive zones; other
resistive zones contained large sandstone boulders believed to be associated with the building of the
Oswego River Barge Canal. Known and potential tar-contaminated zones were the focus of IP
surveys conducted in May through July of 1999. The field experiments conducted at this site were
designed to test the ability of IP parameters to distinguish between types of resistive zones in the
subsurface. Both dipole-dipole and gradient data were collected, targeting zones with the highest
resistivity and surface tar boils.
Results indicate that maps of chargeability at early times on the decay curve indicate the
presence of tar. In addition, Cole-Cole parameters calculated from the decay curve for exponent c =
0.25 were used to generate amplitude, phase and critical frequency values. Maps of these values
also separate zones of tar contamination from sandstone boulders and other resistive zones.
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A Regional Groundwater Evaluation Using Magnetotelluric Soundings For Monclova, Mexico
A regional groundwater evaluation and exploration project was completed for the city of Monclova, Mexico in
1998. Monclova is located in the desert (13.7 inches rainfall per year) and is dependent upon groundwater for its
municipal and industrial resources. Its population (332,000) is expected to grow to 1,200,OOO by 2046. The
municipal wells are completed in Cretaceous carbonate units up to 3,300 feet deep and 25 mgd of water is pumped
from the wells. Monclova has a deficiency of 9.4 mgd with a projected shortfall of 91 mgd in 50 years. In addition,
substantial dewatering of the aquifer is due to over pumpage.
The study began with an evaluation of regional water resources. Previous drilling programs encountered large
variations in production between closely spaced wells. The main aquifers are steeply dipping fractures and faults
generally located in the vicinity of the axis of large anticlinal structures forming the local mountain ranges in the
Coahuila folded belt of Northern Mexico.
A magnetotelhnic (MT) was conducted to assess new well sites to meet the long and short term shortfalls. A total of
77 MT soundings were conducted along nine profiles with the Stratagem system (Geometries). The profiles were
conducted to find favorable structural targets in the dolomite aquifer at depths up to 3,000 feet. The profiles were
located as the result of photo geologic interpretation of the structural geology of the area. Bostick transformations of
the profiles were constructed and the soundings were one-dimensional modeled and correlated into geologic crosssections.
Four wells were drilled on the basis of the MT data. The wells were all excellent producers and make a combined
total of Smgd.
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