- Home
- Conferences
- Conference Proceedings
- Conferences
18th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
- Conference date: 03 Apr 2005 - 07 Apr 2005
- Location: Atlanta, Georgia, USA
- Published: 03 April 2005
121 - 140 of 146 results
-
-
Using Time-Domain Electromagnetics To Map The Transition of An Aquifer To An Aquitard
Authors David J. Hart and Curtis L. ThomasThe Eau Claire Formation laterally transitions from a sandstone aquifer to a shale aquitard in
southern Wisconsin. We used a geophysical method, time-domain electromagnetics (TEM), to map that
transition along two 15-mile transects. Available geologic well logs located on the transects show no
shale to the west, a shale thickness of more than 100 feet at the transects’ centers, and thin shale to the
east. Using well logs alone, we could not precisely locate the edge of the shale aquitard or the determine
nature of the transition between the sandstone aquifer to the shale aquitard.
Our TEM surveys agreed with the well logs, provided a better location of the edge of the shale
aquitard, and showed a gradual thickening and deepening of the shale at the center of both transects. To
reduce equivalence common in electrical methods we used formation resistivities taken from normal
resistivity measurements in the geologic formations encountered in the TEM surveys. These TEM
results can be used to develop better geologic models of the Eau Claire Formation; incorporating the
transitional nature of this formation from sandstone to shale will help to provide more realistic
groundwater flow simulations for this region.
-
-
-
Characterization of A Fractured Aquifer Using Multicomponent Seismic Data
Authors Nedra D. Bonal and Clark R. WilsonNine-component seismic equipment from the Network for Earthquake Engineering Simulation
(NEES) at the University of Texas is used to determine relationships between seismic and hydrogeologic
properties in a near-surface aquifer. The study area is a fractured limestone in the recharge portion of the
Edwards aquifer in Hays County south of Austin, Texas. Experiments are developed to measure
fracture-related seismic anisotropy and its relationship with the hydrogeologic characteristics of the
aquifer. One of the NEES seismic sources is a small vibrator capable of generating waves up to 500 Hz.
Three-component data from a traditional hammer source are also recorded.
The goal of this study is to estimate in situ fracture parameters of orientation, density, and filling
material from seismic data. Estimation of these parameters should be useful for determining
groundwater flow and storage, evaluating recharge enhancement, and understanding environmental
remediation of fluid contaminants.
-
-
-
Seismic Reflection Imaging of Suspected “Windows” In The Upper Confining Unit of The Memphis (Tennessee) Aquifer
Authors Angela B. Pell, James B. Harris and Brian A. WaldronUntil recently, the Memphis (Tennessee) aquifer was believed to be well protected from
downward vertical seepage of urban surface waters and groundwater in the surficial (shallow) aquifers
by clay-rich layers of the upper Claiborne confining unit. However, recent studies of the Memphis
aquifer and upper Claiborne confining unit show evidence of “windows” through the confining layer in
the Memphis area. To investigate the size and structure of these confining layer breaches, S (shear) -
wave seismic reflection profiles were acquired at two locations in the Memphis area. The reflection data
were collected in SH mode (sensitive to horizontally polarized shear waves) and the seismic energy was
generated by horizontal sledgehammer impacts on a steel I-beam oriented perpendicular to the spread.
Data quality is moderate with variable amplitude, coherent reflection energy on all of the profiles.
However, parts of the profiles are dominated by diffracted energy, indicating complex stratigraphy
and/or structure. The most significant features imaged on the seismic data are near-surface
paleochannels (~ 140 to 350 m wide) cut into and through the confining layer, that may provide a
hydrologic connection between the surficial (paleochannel fill) and Memphis aquifers.
-
-
-
Using Cpt To Estimate An Aquifers Heterogeneity
Authors Axel Tillmann, Zsuzsanna Nyari, Andreas Englert, Imre Fejes, Jan Vanderborght and Harry VereeckenThe intensive growth of industrial and agricultural activity causes an increase of polluted
areas. In order to predict the spreading of near-surface contamination it is essential to be familiar
with the hydrogeological parameters of the investigated earth. The cone penetration technology
is capable to resolve the structure of the subsurface in detail and logs various physical parameters
during soil penetration. Cone penetration tests (CPT) were performed at the test site Krauthausen
to investigate the aquifer's heterogeneity in detail.
We present the results of the CPT survey at the test site and the estimated three dimensional
heterogeneous distribution of physical soil properties. We estimated the hydraulic conductivity from
those data using regression analysis. Therefore the CPT method is capable to gain a spatial, highly
resolved data set of the hydraulic conductivity distribution. Furthermore we used this data set
to estimate the spatial heterogeneity of hydraulic conductivity, i.e. the correlation length and
anisotropy within the aquifer.
-
-
-
Possible Extent and Depth of Salt Contamination In Ground Water Using Geophysical Techniques, Red River Aluminum Site, Stamps, Arkansas
Authors Gregory P. Stanton and Wade KressA surface-geophysical investigation of the Red River Aluminum site at Stamps, Arkansas, was
conducted in cooperation with the Arkansas Department of Environmental Quality to determine the
possible extent and depth of saltwater contamination. The two-dimensional, direct-current resistivity
method identified resistivities less than 5 ohm-meters which indicated possible areas of salt
contamination occurring in near-surface or deep subsurface ground water along four resistivity lines
within the site. One line located east of the site yielded data that demonstrated no effect of salt
contamination. Sections from two of the five data sets were modeled. The input model grids were
created on the basis of the known geology and the results and interpretations of borehole geophysical
data. Data from the resistivity lines indicate both near-surface and subsurface saltwater contamination.
The near-surface contamination appears as low resistivity (less than 5 ohm-meters) on four of the five
resistivity lines, extending up to 775 meters (2,542.8 feet) horizontally in a line that traverses the entire
site south to north. Model resistivity data indicate that the total depth of saltwater contamination is about
18 meters (59 feet) below land surface.
-
-
-
A Comprehensive Geophysical Case Study at A former Radioactive Waste Disposal Site In The Columbia River Valley, Southeastern Washington
More LessAs part of a site investigation, sponsored by the United States Department of Energy, at the
Hanford superfund site in southeastern Washington, a magnetics, electromagnetics (EM), and resistivity
survey was completed. A dense coverage of geo-referenced EM and magnetics data was simultaneously
obtained over the 50-acre site to delineate the location of buried waste disposal trenches in the Hanford
alluvial formation. Radioactive contaminants of concern in the trenches consisted of Uranium,
Plutonium, Cesium, Strontium, and Technetium. The EM and magnetics results confirmed suspected
trench locations and the location of pipelines used to transport the liquid waste to the trenches.
High resolution resistivity (HRR), conducted in a pole-pole array, was used to image the vertical
and lateral distribution of the electrical resistivity beneath a single trench. Five parallel lines of lengths
200m to 300m and spaced approximately 8m apart indicated that the plume has migrated downward
from the trench to 30m below ground surface. A hydraulically resistive layer of fine silt has
significantly impeded the plume from reaching the water table. An additional line, which bisected
several trenches, suggested that the plume is extensive and the contributions from each trench combine
to form a single contiguous plume. Remediation strategies are currently being considered.
-
-
-
The Use of Geophysics To Map Low Level Radioactive Waste Disposal Sites at former Air force Weapons Storage Areas
Authors Richard P. Allen and Ronald A. CrowsonAnecdotal reports of the burial of wipes, personal protective clothing, and other items used in the
maintenance of early weapons systems prompted the Air Force to initiate a series of investigations to
characterize the weapons storage areas (WSAs) at several former Strategic Air Command (SAC) bases.
These investigations are being conducted at five former SAC bases that were closed and are being
redeveloped, so it is important to ensure the public is protected against potential exposure to low levels
of radiation.
As specific information about weapons maintenance activities is 45 to 50 years old, and since
these activities took place during the height of the Cold War, when secrecy and “need to know” were
paramount to maintaining our national security, the record is disappointingly sparse.
Investigations consisted of radiological measurements in open areas and inside buildings, and a
dual-disciplined geophysical study, with primary reliance on multifrequency electromagnetic profiling
(EM) to characterize areas of interest. Traverse separation was 5 feet, a parameter dictated by the
anticipated size of the target. EM anomalies were further characterized with ground penetrating radar
(GPR). A test-pitting program at one of the bases confirmed the interpretation of several geophysical
anomalies, none of which represented targets of interest.
-
-
-
Computer Simulation of Hydrocarbon Flow and Wave Field for Interpretation GPR Measurements In Contaminated Sites
Authors Henryk Marcak and Tomislaw GolebiowskiLocation of hydrocarbon contamination in the ground using a GPR system should be preceded
by a choose of the interpretative model. Four models i.e. Plume, Layer, String and Stochastical have
been described in the paper. Each model is dependent on the elapsed time since the initial discharge of
contaminants and the GPR surveys. The GPR measurements carried out in contaminated areas, after a
long time from discharge, showed the importance of Stochastical Model in interpretation of GPR data.
-
-
-
High Resolution Ground Penetrating Radar Investigations In The Archeological Site of Cavallino (Lecce, Italy)
Authors Giovanni Leucci and Sergio NegriA Ground Penetrating Radar (GPR) survey was been carried out in the archaeological site of
Cavallino (Lecce, Apulia, Italy) in collaboration with the Dipartimento di Beni Culturali of the
University of Lecce. The archaeological site of Cavallino, located only 6 kilometres south-east of
Lecce, corresponds to an enormous settlement, about 70 hectares large, of notable historical
importance.
Keeping in mind the vastness of the site, the archaeologists selected an area, of about 4000m2, for a
systematic archaeological excavation. Contemporarily, GPR investigations using high-resolution
acquisition techniques (parallel profiles at 0.25 m spaced) were performed in a test-zone located
inside the same area. The objective of this preliminary geophysical investigation was to verify the
effectiveness of the technique for a spatial definition of the archaeological structures with nondestructive
methods, in view of their application in the rest of the site, that, for obvious reasons,
could not be entirely excavated in brief times.
The GPR data, previously processed, were used for 3D representations, in order to visualise in a
more effective manner the three-dimensional position of the anomalies evidenced in the single radar
sections. The results obtained in the survey underline the presence of structures of regular shape
related to the presence of walls confirmed by the excavations that are still in progress.
-
-
-
3D Imaging Archaeological Tomb By Vertical Electric Soundings
Authors Keisuke Ushijima, Hideki Mizunaga, Toshiaki Tanaka and Kazuo MiyamotoApplication of geophysical methods has increased to investigate near-surface horizons of
interests in related to environmental and engineering geophysics because geophysical methods are
cost-effective and large areas can be quickly surveyed at relatively low cost without borings and trench
excavations. The most productive geophysical methods are Ground Penetrating Radar and Electrical
Resistivity methods for which the target exhibits the greatest physical contrast with respect to the
surrounding formations. However, the geoelectrical geophysics is very difficult to predict the
sub-surface using conventional techniques because of the shortage of the resolution. These geophysical
techniques have required upgrading of data acquisition accuracy of the methods using a multichannel
resistivity tool such as Handy Archaeological Resistivity Meter developed by the joint research of
Kyushu University and OYO Corporation in Japan. Geoelectrical methods have the economic
advantages to solve various archaeological problems. However, there was no successful 3D computer
program required for interpreting observed apparent resistivity data. In the present paper, a robust 3D
computer program was developed and applied to archaeological prospection. Results of 3D inversion of
VES data are compared with the results of GPR method and evaluated with archaeologists of
Archaeological Society of Japan.
-
-
-
Cavity Detection By Dc Resistivity Imaging In Khalifa City B, Emirate of Abu Dhabi, Uae
Authors Baoshu Li, Ali Taleb and Hassan Al JafriUnderground cavities associated with the dissolution of gypsum and now filled with saline
ground water were encountered during the construction of infrastructure in Khalifa City B, Emirate of
Abu Dhabi. Heavy ground water flow through the cavities delayed the works for months. Moreover the
cavities are considered hazardous to the future civil works. DC resistivity imaging technique was
employed to detect the cavities, which are characterized by resistivity lows due to the infilling of saline
ground water. Quality analysis of field resistivity data was set as the first step of data interpretation
because poor quality data, mainly resulting from the dry fill materials at the surface result in false
resistivity anomalies not relevant to cavities. The pole-pole array was found the most suitable method to
provide cost-effective and accurate field data and reliable results. Cavity detection included the
identification of cavities and estimation of their vertical thickness, lateral extension and depth of cavities
below the existing ground surface. The cavity-related resistivity anomalies disturb the surrounding geoelectric
layers and form low resistivity window zones and shadow zones on both apparent and inverted
resistivity sections. The ability of DC resistivity imaging technique to define detailed features of cavity
depends significantly on calibration boreholes and careful interpretation of the data.
-
-
-
Lessons From Northern Alabama: Multi-Technique Geophysical Investigation Characterizing The Bedrock and Fracture Network
Authors John M. Bartos Jr., Robert K. Davis, Dr. Bradley J. Carr and Colin MellorGolder Associates Inc. (Golder) and Geophex, Ltd (Geophex) performed a geophysical
investigation at a closed manufacturing plant in Alabama. This investigation used multiple geophysical
techniques (surface and borehole) to characterize the unconsolidated and limestone-shale bedrock at the
facility. Seismic refraction and direct-current resistivity distinguished areas of high permeability zones
(lineaments) across the site and offsite. Induced polarization was used to locate areas of NAPL in both
the residuum and bedrock. Borehole geophysical logging characterized the lithology, water-bearing
fractures, and distinguished the different fracture networks present on the site.
-
-
-
Facilitating The Incorporation of Geophysics Into Geotechnical Practice
Authors F. Alex Rutledge, Dr. Matthew Mauldon and C.J. SmithAlthough geophysical methods have long been a mainstay of oil and gas exploration, they are not
yet routinely used in geotechnical practice. Recent advances in computing technology and reduced cost
of geophysical equipment have led to many advances in high-resolution geophysics that can be applied
to site investigation of engineering projects. Advances in these techniques and their applications,
however, have not been sufficiently communicated to practicing engineers. A Primer on Geophysics for
Geotechnical Practice has been prepared to help communicate basic understanding, advances,
applications, and limitations of the most commonly used geophysical techniques to practicing engineers.
The project engineer is often the one who determines the extent and type of subsurface investigation
needed, and, therefore, the dissemination of this information to the engineering community is critical for
the advancement of near-surface geophysics. A better understanding of the applications and limitations
of geophysical techniques within the engineering community will lead to more efficient site
investigation, and reduced costs associated with encountering unexpected subsurface conditions.
-
-
-
Slope Stability Analysis of The Iliamna Volcano, Alaska, Using Aster Tir, Srtm Dem, and Aeromagnetic Data
More LessI use thermal IR and digital elevation models to create a hazard index that characterizes slope
stability on active volcanoes using Iliamna, Alaska as a case study. ASTER and SRTM data were
processed and scaled, then a script was run to plot the hazard index based on hydrothermal emissions
and topographic slope. The plots display areas at risk for slope failure, which correlate well to the
geologic field studies. These scripts can be run quickly and easily to improve field safety for geologists,
geophysicists, and other field crews.
-
-
-
Sonic Log To Estimate Engineering Characteristics of Deep Mixed Columns
Authors Ali Porbaha, Farid Ghaheri and Anand J. PuppalaThe results of a series of sonic log tests are presented to estimate engineering characteristics
of deep mixed soil cement columns of 900 mm in diameter treated up to a depth of 13 m using deep
mixing (DM) technology. Deep mixing is a ground modification technology that blends soil in situ
with a cementitious material, such as cement or lime, using specially designed equipment with
augers and paddles. Data obtained from the field are compared with those from core samples tested
using unconfined compression tests. The results show that porosity of the cement treated soil is in the
range of 40 and 44 percent, while the shear wave velocity varies between 595 and 1471 m/s. A linear
equation correlates porosity and shear wave velocity. In addition, the porosity of the soil generally
decreases with increase in soil’s compressive strength; and a linear equation represents the variations
in porosity with regard to the unconfined compressive strength. For the treated soil columns the
radioactivity ranges between 70 and 137 cps, while compression wave velocity changes between
1786 to 2500 m/s. The details of filed test, shear wave and compression wave velocities, shear and
Young’s moduli, porosity, and some correlations of field data with laboratory tests are presented.
-
-
-
Evaluation of Linearity of First Mode of Vibration In Resonant Column Testing
Authors Zahid H. Khan, Giovanni Cascante and Hesham El NaggarThe shear strain along the height of a specimen in resonant column testing (ASTM D4015-92) is
assumed to vary linearly when evaluating its dynamic shear modulus and damping ratio. To examine
this assumption, specimens of dry sand, mine tailings, and cemented sand are tested at different
confinement and shear strain levels. The coupling between the cemented-sand specimen and the top and
bottom platens is enhanced using three different agents: gypsum cement, Portland cement, and epoxy
resin. The mode shapes are measured using a miniature accelerometer that is attached to the specimen at
predefined elevations and a reference accelerometer placed at the top of the specimen (driving plate).
The dynamic properties of the specimens are computed from the responses of both accelerometers. The
measured mode shapes for dry sands and mine tailings are linear but the cemented-sand specimen
displayed a nonlinear behavior in terms of the mode shape and change in dynamic properties with the
strain level. The accuracy of the measured mode shape and dynamic properties is improved as the
coupling between the specimen and the platens is enhanced. The epoxy resin produced best coupling,
followed by Portland and gypsum cements, with the latter two only effective at low confinement and
strain level.
-
-
-
GPR and Archaeological Excavations at The West Point Foundry, New York
Authors Kimberly Finch and Charles T. YoungThe West Point Foundry in Cold Spring, New York, was a major producer of ordnance during the Civil War and manufactured sugar machinery, railway locomotives, and the nation's first locomotive. Now, it lies forested and disheveled with only wall foundations visible on the surface. Conventional archaeological methods provided information on site history and evolution, but the location of buried water channels remained unknown. The channels were used to supply for a giant water wheel which powered machinery. Ground penetrating radar was chosen to search for the channels because it was relatively rapid to deploy, and the data directly reveal the depth dimension. Small scale surveys were carried out at nine assessable areas within the site which were thought to contain the channels. Direct evidence of the subsurface was obtained by excavating at radar anomalies. All structures excavated were not water channels but will prove useful in interpreting the history of the site.
-
-
-
A Simple and Effective CDI Analysis Software
Authors Garret A. Veloski and Ronald J. LynnA conductivity depth image (CDI) viewer program was developed for analysis of airborne EM
data inversions created in EM Flow and EM1DFM. The software was written in LabVIEW 7.0 for the
Windows platform and features an assortment of tools. The CDI intensity plots can be color-enhanced
programmatically according to image statistics. The cursor positions in CDI profiles are geographicallylinked
to an ActiveX imagery window with moving map capabilities and real world coordinates.
Apparent conductivity sounding profiles can be viewed simultaneously for any X-position along the
length of the geo-linked CDI image. The user can create custom map underlays in ECW compressed
image format using free software available on the Web. Features of interest can be selected/edited and
added to a list for export into a GIS or GPS compatible format. The CDI images can also be exported in
geo-referenced ER Mapper BIL format or HTML. The application can be bundled with 1D inversion
data and distributed with an installer to customers royalty-free.
-
-
-
Quality Control/ Quality Assurance Software for Digital Geophysical Mapping
Authors Amy N. Walker and Lorraine GodwinThe Huntsville Center has been developing Quality Control/ Quality Assurance
(QC/QA) techniques and documentation to promote more consistent, higher quality
geophysical investigations. The Center partnered with Geosoft Inc. under ESTCP funding
to develop these techniques into a software package that runs under their Oasis montajTM
platform. The principal goals of the project include: standardization of QA/QC processes
within the UXO community, improved data quality, improved detection methods and to
provide a standard software platform for algorithm sharing. The software package has
been supported and applied in the field since April 2002, with continuing enhancements
and additions to evolve into a capable tool set. Utilizing the standardized software tools
and techniques developed under this project will help ensure acceptable quality standards.
-
-
-
Landmine and Uxo Discrimination Using Beam forming Tomography
Authors David Tillson and Beiyuan LiangThis paper presents results of processing landmine and UXO data collected with a
3-D GPR system using beam forming tomography. We provide a brief summary of the
beam forming tomography concept for discriminating UXO based on processing data
provided by the EPFL\LAMI\DeTec project Lausanne. Using this technique the efficacy
of producing high-resolution 3-D images using synthetic GPR array processing was
demonstrated. We follow by a description of a new wide band linear array GPR system
that uses step-frequency continuous waveform (SFCW). This 3D-GPR system is capable
of operating in a stand-off mode; surveying a 2.4 meter swath at speeds up to 5 km/hr;
penetrating depths > 2 meters; and providing 5 cm object resolution. Results of
processing landmine and UXO data collected from a European training site with this
system are presented. A comparison of real time low-level data processing capabilities
provided with the 3D-GPR system and advanced beam forming tomographic imaging and
analysis capabilities using a separate software package is provided.
-