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9th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
- Conference date: 28 Apr 1996 - 02 May 1996
- Location: Keystone, Colorado, USA
- Published: 28 April 1996
121 - 134 of 134 results
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Keys To Marketing And Selling Environmental & Engineering Geophysics
Authors Douglas E. Laymon and Martin MieleMuch of the time as practicing geophysicists we have rightly focused our attention on
refining and developing our craft, technical ability, and know-how. Throughout our early
education and early technical work, geophysicists gain the necessary tools to be good practitioners
of their science. However, we are most often left to our own devices to learn the business and
selling skills required to obtain and maintain the work that brings satisfaction to our careers as
geophysicists. This paper focuses on some of the essential tools that can be used in selling and
marketing geophysics to others (e.g., engineers, attorneys, and developers).
Three essential keys are important to selling. First, you must have a sellable commodity.
As geophysicists this is our technical know-how, ability, and experience. Secondly, you must have
enthusiasm for what you are doing. You must genuinely enjoy and believe in geophysics and what
it can do for your client. Your clients and potential clients will see this and will get caught up in
your enthusiasm. Thirdly, you must have a strategy for your approach, or a marketing plan which
outlines your approach to selling and provides you with a road map to follow. Additionally, you
must be able to understand your client’s needs. It is important to keep the lines of
communication open with clients, as communication is paramount and will determine the amount
of follow-on work and types of referrals you receive.
Marketing and selling is the “work of getting work.” Networking and the development of
relationships is the bottom line in sales and marketing. People work with people and generally
contract people they trust and like. Winning at sales takes common sense and diligent effort.
The fruit of this labor is continued success and growth of your business. To the geophysicist, sales
is a means to an end which allows you to be involved in the work you enjoy and to help bring
fulfillment to your career as a geophysicist.
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The Value Of Two-Component Gpr Data: Identifying The Polarization Contribution In Amplitude Anomalies
Authors Rob D. Luzitano and Tad J. UlrychMost of the current research in ground penetrating radar (GPR) relating reflection strength to material properties,
such as soil moisture and the existence of contaminants, involves only single component data, i.e., the component
with transmitter and receiver antennas parallel. This scalar view of a vector phenomenon leaves most of the
information contained in the reflected wavelet untapped. Moreover, an amplitude anomaly in the parallel component
may be largely, or at least in part, due to a polarization effect. Anomalous polarization of the returned wavelet
degrades the coupling with the receiver antenna since the match between wavelet and antenna polarizations is
decreased. This polarization contribution is ignored by the common scalar approach which ascribes the amplitude
anomaly entirely to such properties as water saturation or a suspected contaminant plume. Wavelet depolarization
occurs, to some degree, for most cases of reflection and refraction. Indeed, the depolarizing character of a scatterer
can aid in its identification. Although complete depolarization, causing reflections to extinguish, was confirmed 20
years ago in sea ice, little attention has been given to possible depolarization effects in soil or rock.
We investigate the power loss in the parallel component due to anomalous polarization by using a new instantaneous
attribute: polarization match. The instantaneous polarization match estimates how severely depolarization
is affecting amplitudes while also identifying the responsible depolarizing structure. In this initial investigation
the instantaneous polarization match estimate is applied to data from sites of two different structural complexities.
Field experiments at an abandoned overpass ramp investigated depolarization for the simple cases of smooth
shallow dipping interfaces and a lateral change in material. Both profiles and common midpoint (CMP) soundings
demonstrated that the transverse magnetic (TM) wavelet depolarizes more than the transverse electric (TE) wavelet.
This difference is, at least in part, explained by the occurrence of the Brewster angle in the TM mode. At the
sites investigated, the most significant mechanisms for depolarization appear to be scattering from rough spots (a
S-20% power loss) and at points of wavefront interference. These surveys provide only an initial investigation, and
other traverse orientations, environments, and target types should be investigated, some of which are likely better
depolarizers than the targets in this study.
Although degraded polarization match is usually a secondary amplitude effect, in some cases this problem
could become significant. When pursuing targets of anomalous amplitude, or any other attribute, at least one
two-component profile should be acquired to characterize the depolarization nature of the field site.
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An Integrated Geophysical Investigation Of An Inactive Wood Treatment Facility
Authors Jyotiranjan Kar and Peter T. MillerFive geophysical methods were used to characterize the subsurface at an inactive wood treatment facility. Seismic refraction,
electromagnetic conductivity (EM-3 1 and EM-34), very low frequency (VLF), and spontaneous potential (SP) methods were used to
locate potential water-bearing zones and to help understand the driving mechanisms for the movement of groundwater and chemical
constituents below the site. The investigation was successful in delineating areas where gravity drainage, groundwater seepage, and
preferential groundwater movement was occurring. Typically, these areas were characterized by lower bedrock elevations, decreased
bedrock velocities, increased electrical conductivity values, and anomalous VLF and SP deflections. The data were incorporated into
the generation of site models, the determination of critical geologic information, and the placement of seven proposed monitoring
wells.
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2D Inversion Of Resistivity Profile Data
Authors Ingelise Møller, Niels B. Christensen and Bo H. JacobsenProfile oriented geoelectrical data can now be collected with considerable speed and with short sample
length resulting in huge amounts of data values per day. For dense galvanic profile measurements we
have developed a 2D inversion algorithm; a deconvolution based on the Born approximation and the 2D
FrCchet kernel. The translational invariance of the problem allows the development of an algorithm in
the wave number domain, whereby the inversion problem decouples into many small linear problems.
The deconvolution algorithm is demonstrated on a theoretical data set and a CVES (continuous vertical
electrical sounding) profile of field data. Besides these vertical sections, data are presented as traditionally
iso-resistivity maps of apparent resistivity and of layer resistivity - results of the deconvolution algorithm.
The deconvolution algorithm works almost instantaneously with computation times in order of seconds
on an ordinary PC for 500 measurements in 10 configurations.
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A Site Characterization Of The Soda Butte Creek Drainage, Yellowstone National Park
Authors Eric Nyberg, Wayne L. Hamilton, William R. Sill and Marvin A. SpeeceGeophysical techniques were applied in the Soda Butte Creek study in an attempt to characterize the area’s
groundwater resource. The head of this drainage is located near the northeastern boundary of Yellowstone
National Park; furthermore, Soda Butte Creek is a major tributary of the Lamar River--which in turn is a
major tributary of the Yellowstone River. The National Park Service is concerned with potential development
along the Park’s boundary which may adversely affect both surf&l and groundwater recharge into the Park.
Seismic refraction surveys and Schhnnberger resistivity soundings have been used to define the area’s valley
Ii11 composition and thickness. The techniques were also used to determine the valley’s saturated thickness.
By obtaining these parameters through geophysical means, important insights pertaining to the area’s
hydrogeology can be developed. Since no previous hydrogeologic studies (i.e., pump tests) have been
performed in this environmentally sensitive location--due, in part, to the costs and impacts associated with
drilling water wells--the use of cost effective, low-impact geophysical methods is a viable means of obtaining
subsurface information.
The application of both seismic refraction surveys and Schlumberger resistivity soundings was done in an
attempt to verify the results of each technique. By accomplishing this feat, the problem of “nonuniqueness”
associated with each method can be significantly reduced.
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Environmental Geophysics And Sequential Air Photo Study At Sunfish Lake Twin Cities Army Ammunition Plant
Authors C.A. Padar, L.D. McGinnis, M.D. Thompson, A.W. Anderson, M.A. Benson, J.E. Stefanov, C.R. Daudt, S.F. Miller and D.E. KnightGeophysical and air photo studies at the Twin Cities Army Ammunition Plant (TCAAP), Minnesota,
were conducted to establish a chronology of dumping and waste disposal. This study was undertaken to aid in the
assessment of the amount of remediation needed to reclaim a wetland area. An integrated analysis of
electromagnetic, magnetic and ground-penetrating RADAR (GPR) measurements over a 25acre site, provided the
information necessary to define waste disposal events. These events are observed on a sequence of aerial photos
taken between 1940 and 1993.
The former southwestern embayment of the lake, filled in during the original construction of the base,
has been clearly defined. Two burn cages and their surrounding debris have been delineated. The area1 extent of
another waste site has been defined along the northern shoreline. Depth estimates determined from EM-61
analysis, and depths to original lake bottom, derived from GPR, have yielded volumetric estimates of the amount
of material that would need removal if excavation is required. Magnetic and electromagnetic data have pin pointed the locations of mounds, observed from historical air photos. Except for these areas along the northwestern shore, there is no evidence of waste disposal along the shoreline or within the present-day lake margins. The ability to date the anomalous regions is
significant, in that different production demands upon TCAAP, during the time periods of WWII, The Korean War, and The Vietnam Conflict, have resulted in different types of waste. The ability to categorize areas with distinct time periods of operation and waste disposal can greatly aid the environmental cleanup effort with regard to the type of contaminants that might be expected at these poorly documented disposal sites.
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Small-Scale Mineral Cavity Exploration Utilizing High-Resolution Ground-Penetrating Radar
Authors J.L. Petruccione, C.E. Papadakis, R.W. Welhrer, MA. Becker, R.R. Franke and P.S. MosesIn order to test the exploration potential of ground-penetrating radar (GPR) for mineral-lined cavity
detection, a GPR survey was conducted over a relatively smooth, -5 m2 bedding plane surface located within
an open-pit limestone mine, east-central New York State. Mineral cavities within the siliceous limestone are
observed on near-vertical surfaces and range between 0.2 to 0.8 m below the exposed bedding surface, upon
which the survey was performed. For this investigation, a hand-held, shielded 1000 megahertz (MHz) transceiver
antenna was utilized, and subsurface reflections were sampled over a 20 nanosecond (ns) time window which
provided a maximum penetration depth of -1 m. A 1 x 1 ft (0.3 x 0.3 m) grid was marked on the exposed
bedding surface, and GPR profile data were then collected by sliding the 1000 MHz antenna at a relatively
constant rate over the established grid lines in perpendicular, intersecting directions.
All GPR data were collected as analog chart records which allowed real-time, in-field interpretations.
Radar facies observed during this survey include laterally continuous, high-amplitude reflections that have a
subparallel to parallel geometry. These reflections are prominent between 4 and 14 ns two-way travel time
(TWT), and are interpreted as either internal bedding plane interfaces, fractures, or solution (stylolite) surfaces.
Several high-amplitude reflectors between -4 and 10 ns TWT were observed and characterized by an arching,
hyperbolic-shaped geometry. Steeply inclined diffractions that cross-cut prominent lateral, parallel reflections
are also associated with the hyperbolic reflections. This facies relationship is attributed to the contact between
bedrock and air-filed voids within bedrock. A total of 10 air-filed voids were predicted from the GPR survey.
Physical sampling of these GPR anomalies uncovered a total of six, near-circular to ovoid, dome-shaped, minerallined
cavities. Based on the survey fmdmgs, the high-resolution 1000 MHz GPR system can be used to accurately
map internal bedrock structures, in particular, shallow (c 1 m subsurface) air-filled vugs.
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Dielectric Properties Of Polluted Soils As A Potential Tool To Detect Low Level Organic Pollution In Unsaturated Soils
Authors Sylvie Porokhovoï, Jean du Mouza and M. ReiterThe detection of organic pollution in soils is usually made by chemical analysis. Some geophysical methods are
available to detect massive and transient pollution. But the standards used in Europe to define a non polluted soil
are very strict : some organic compounds (as Polycyclic Aromatic Hydrocarbons) have to be less than 10 ppm.
Hence, a geophysical tool allowing to prospect large areas with low rate organic pollution has to be developed.
In this aim, our work is the first step of the evaluation of a geophysical method based on the dielectric
characteristics of soils, our final goal being in situ measurementso f those parameters.
Several geophysical methods are already used to monitor organic pollution of groundwater. Both electric
(Olhoeft G.R., 1985) and dielectric properties of these pollutants can be used. Conventional DC resistivity
measurementsa nd EM methodsc an provide good results when polluted groundwater is linked with high salinity,
while GPR and radiowave EM can be used to detect hydrocarbons by measuring soil dielectric properties. The
problem of detecting organic compounds is different for saturated and unsaturated media because the dielectric
constant E, of water (- 80, depending on temperature and frequency) is higher than that of dry soils (2<&,<6) and
organic liquids (E,, < 6 if the compound is not polar). For saturated soils or rocks, the presence of organic liquid
reduces the water saturation component and, consequently, the global dielectric constant of the soil in
comparison with non-polluted soil or rock. GPR method can detect contrasting dielectric permittivities due to
such phenomena. This method is efficient for high levels of pollution ( > 30% by weight) in a saturated zone and
for transient flow because it is easier to compare several GPR sections versus time than to interpret one section
without references. Our bibliographic study indicated the lack of geophysical methods to detect low level
organic pollution, but some papers appear to be optimistic (Yong R.N. and Hoppe ES., 1989, Vanhala H. and
al, 1992) concerning the detection of pollutants in soils measuring the dielectric behavior in polluted soils.
Consequently, we made some laboratory measurementso f the dielectric properties of both polluted and non
polluted soils.
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Gravimetric Mapping Of An Abandoned Underground Limestone Mine In Clark County, Indiana
By R.M. RenéAn underground limestone mine near the center of Clark Military Grant 48 in Clark County, Indiana, was in
operation from 1892 to 1896. This mine, here referred to as the Gheen’s Mill Cementville Mine, was abandoned and
became flooded before the slope shaft entrance was back-filled. The roof of the mine is at a depth of about 8.2 m (27
feet). An interval of 4.3 m (14 ft) or less of limestone was mined to make a natural cement. A map of the mine was
needed because undermined areas might be unsafe for buildings. The area is presently being developed as a business
park. Fifty-six holes were drilled several years ago to map the mine, but their precise locations were unknown.
Seventeen holes found cavities, 32 holes penetrated the mined interval but did not encounter cavities, and 7 holes did
not find bedrock within a depth of 11 m (33 ft). A gravity survey was made to help locate these holes and to better
define the bounds of the mine. One hole was successfully exhumed and identified on the basis of the gravimetry.
Gravity was measured at 837 stations in nineteen east-west and north-south profiles with 3.05-m (loft) station
spacing. Inflection points of a negative 140~pgal Bouguer gravity anomaly located edges of the mine. First and second
horizontal derivatives of the gravity profiles helped locate these edges. Gravity profiles around the mine perimeter
did not detect any tunnels extending between the boreholes. A large negative residual Bouguer gravity anomaly south
of the mine defines a buried valley that limited the area available for mining. The gravity method should be practical
in mapping similar underground mines in the region. Approximately 40 percent of one of these mines, the Falls City
Mine, has collapsed (Ren6, et al., 1994). The gravity survey of the Gheen’s Mill Cementville Mine probably indicates
that a lesser proportion of the limestone was mined within the perimeter of this mine than in the case of the Falls City
Mine.
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3-D D.C. Electrical Resistivity Inversion With Application To A Contamination Site In The Aberjona Watershed
Authors Weiqun Shi, William Rodi, Randall L. Mackie and Jie ZhangWe have developed an inversion algorithm that finds smooth, three-dimensional models of the earth’s electrical
resistivity from d.c. pole-pole or dipole-dipole potential field data. The algorithm, based on Tikhonov’s
regularization method, computes models that fit the data and have minimum structure in the sense that second
spatial derivatives of resistivity are minimized. A nonlinear conjugate gradient (NLCG) algorithm with
pre-conditioning is employed to solve the minimization problem involved. Numerical experiments with synthetic
and real data show that our version of the NLCG algorithm is more efficient than the commonly used
Gauss-Newton method. We demonstrate the inversion algorithm on a large dipole-dipole data set collected
at a groundwater contamination site in the Aberjona Watershed in Massachusetts. Our Aberjona inversion
model correlates well with other geophysical results at the site (GPR sections and cone penetrometer logs)
and serves to extrapolate the sparse stratigraphic information previously available into a full 3-D model of
the study area.
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An Integrated Geophysical Study Of The Yarmony Archeological Site, Colorado
Authors C. Skokan, C. Edwards, J. Holt and A. VaughanIn a joint project between the Colorado School of Mines
Department of Geophysics and Colorado State University Department
of Archeology, and sponsored by the Bureau of Land Management, an
integrated survey of the Yarmony 5EA759 site was undertaken. The
Yarmony archaeological site was discovered in April, 1987, during
a routine examination for a proposed road improvement and during
that month excavations began. A pit house was discovered which
dated to 6300 years before present. This pit house is the oldest
known dwelling, to date, located in Colorado. Human remains
approximately the same age as the pit house were also found at
Yarmony (Metcalf and Black, 1991). These discoveries have led to
the need to determine the nature and extent of subsurface
cultural deposits at the site in a quick, cost effective,
reliable, and non-intrusive manner. Geophysics is an effective
and proven method for finding the locations of archaeological
features in many areas (Vaughan, 1985) and was therefore applied
at the Yarmony Site.
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Engineering Soil Parameters From Seismic Cone Penetrometer Tests - An Overview
Authors T.A. Terry, D.J. Woeller and P.K. RobertsonSince the introduction of the seismic cone penetrometer test in the early 1980s significant progress has been made in
the analysis and interpretation of the collected data. The basic equipment, test and data reduction are reviewed. The
current methods available for evaluating liquefaction using penetration resistance and normalized shear wave velocity
are presented and discussed, as is the recently developed method for evaluating sand compressibility from penetration
resistance and shear wave velocity.
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Recent Applications Of Electrical Imaging Surveys In The United Kingdom
By Ron D.BarkerRecent developments in electrical tomography field acquisition and data inversion technology
have resulted in the production of electrical images which more accurately mirror the subsurface than is
possible with conventional resistivity surveys. The technique is particularly suitable for shallow site
investigation where understanding the complexities of the subsurface structure is important. This is
demonstrated with examples of its application in determining depth to bedrock, in resource and contaminant
studies, the study of shallow fracture systems, and in monitoring subsurface fluid flow.
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Two Layer Depth Analysis Of Em-3 1 Conductivity Data
More LessThe Geonics Eh4-3 1 Inductively Coupled Ground Conductivity A4eter is a very
useful instrument for rapid and sensitive area1 coverage for site characterization. It
responds to a number of important environmental variables such as soil or rock
type, pore fluid content, and fluid conductivity, and often produces very useful
plan maps. It would be helpful if the results could be augmented with depth
information along selected traverse lines. It is often important to know, for
example, whether an apparent conductivity anomaly arises above or below the
bedrock surface or water table.
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