Innovative High Resolution

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Innovative High Resolution Electrical
Resistivity Imaging (ERI) (Aestus GeoTrax
Survey) Used to Detect Soil/Groundwater
Contamination From Leaking USTs and Other
Sources
Presented by Stuart W. McDonald, P.E. President,
Aestus, LLC
The 11th National Israeli NDT conference
Tuesday, April 27, 2010 Tel Aviv, Israel
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Topics Covered Today

• PROBLEM
• Conventional environmental site characterization
  techniques are and are not producing satisfactory
  results Site cleanup too costly
• Other historically available technology such as
  conventional geophysical tools (GPR, EM, Seismic,
  etc.) not helping enough
• Need new approach/tools look at other
  industries faced with similar problems (oil/gas
  medical)
• SOLUTION
• Environmental consulting and non-traditional
  geophysics experts from Aestus/Oklahoma State
  University teamed to develop a subsurface
  scanning tool that works at virtually any site
• This tool has changed paradigms of contamination
  behavior/distribution in subsurface
• Yields lower project costs and faster cleanup

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Topics Covered Today (continued)

• PROOF THAT IT WORKS ? EXAMPLES ? COSTS
• Review Case Studies
• Validation by EPAs Ada, Oklahoma laboratory
• Validation by State Regulators
• Validation by Environmental Consultants
• Backed up by University Research and Peer
  Reviewed Publications
• QUESTIONS ANSWER SESSION

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Typical Site Characterization
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Recovery/monitoring Well (Typ.)
Defined Contact Location
Actual image from a refinery LNAPL recovery system
Previously Unknown LNAPL
and thus allows reality-based decisions
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WOULD YOU HAVE SURGERY WITHOUT A
CAT-SCAN/MRI/X-RAY? Why do this with your
environmentally impacted sites?
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• Environmental
• Drill
• Probe
• Excavate

• Medical
• X-ray
• MRI
• Sonogram
• Petroleum
• Seismic
• Gravity
• Magnetics

• Environmental
• Drill
• Probe
• Excavate

• Medical
• X-ray
• MRI
• Sonogram
• Petroleum
• Seismic
• Gravity
• Magnetics

And you thought medical surgery is expensive!
Sampling array at the Cape Cod Site over 10,000
subsurface sampling ports. USGS-
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What is Electrical Resistivity Imaging (ERI)?

• Based on
• DC resistivity techniques (gt100 yrs old)
• Computing/electronics power (lt10 yrs old)
• Instead of 10s of data, collect thousands
  (high data density)
• Analogous to Geological Digital Photography
• Provides map of electrical properties of the
  subsurface

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Aestus Proprietary Supplemental Field Equipment
Proprietary OSU/Aestus Data Acquisition Algorithms
Proprietary OSU/Aestus Data Reduction/ Processing
Standard Electrical Resistivity Techniques
High Resolution Subsurface Image That is
Drillable
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How ERI Works Taking the Picture
Four Electrodes Yield One Measurement Data Point
(pixel)
One Data Point or Pixel
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How ERI Works Focusing the Camera
(1.5 m Survey) 271 feet long 54 feet
deep
(2.0 m Survey) 361 feet long 72
feet deep
(2.5 m Survey) 451 feet long 92
feet deep ( Optimal Choice)
(3.0 m Survey) 541 feet long 108
feet deep
Target Imaging Depth
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How ERI Works Developing the Film
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How ERI Works Viewing the Data using 3-D Model
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• Technological Progression
• Data acquisition now 100x faster than 1990
• Data processing now 350x faster than 1990
• Images were not drillable
• OSU/Aestus created dramatically improved images
• Images can see resistive subsurface targets
  others cant

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after Halihan et al, 2005

• Simple LNAPL plume
• Undergone pump-and-treat and a surfactant flush
• At least 92 wells on the site
• Is the site clean now?

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SB-1
268
50 ft wide x 25 ft depth
SB-2
SB-2
Total Petroleum Hydrocarbons (TPH in mg/kg) vs.
Depth
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SB-3
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SB-3
SB-4
2.5
SB-4
Total Petroleum Hydrocarbons (TPH in mg/kg) vs.
Depth
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Separate Blobs
SB-5
SB-6
Total Petroleum Hydrocarbons (TPH in mg/kg) vs.
Depth
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Data Density Comparison NAPL Site
Sampling data indicate that these monitoring
wells are clean.
Aestus GeoTrax Survey shows that monitoring
well data was not representative of site
conditions Actual Research Site - Anomaly soil
sampling data provided by EPA Ada, OK Laboratory
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To approach the data density of an Aestus GeoTrax
Survey, approximately 35 monitoring wells/soil
borings would be required every 5 feet along a
185 ft transect
At US3,500 per monitoring well, cost would be
US122,500 and takes weeks At US2,500 per
GeoTrax Survey, cost would be US2,500 and take
only 2-3 hours Above budgetary costs do not
include mobilization/demobilization survey costs
vary depending on site constraints
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• This is a magic bullet ?

SB-2
?This is not
Complex sites are still complex, you just have a
better tool to obtain sufficient data.
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• Every site is different- there are infinitesimal
  combinations of lithology, pore fluids, pore
  structure, contamination, and previous
  remediation attempts.
• We dont have a magic resistivity scale that
  categorizes every site.
• Images MUST be calibrated in order to provide the
  best interpretation.

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• Other Potential Applications in Israel
• Sinkhole Detection
• Clandestine Tunnel Detection

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• For Finding Tunnels/VoidsIn Subsurface
• Computer Modeling Predicts
• Success Using GeoTrax Survey
• Failure Using Standard ERI

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(GeoTrax Survey)
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(Not enough resolution to detect small
tunnels confirmed by Israel MOD testing)
(GeoTrax Survey)
(Data indicates probable success untested to
date)
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TunnelTrax Survey(Conceptual Approach)Scale-Up
to Provide Continuous Subsurface Scanningat
Country Border
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• Sink hole detection
• Homeland Security Terrorist Tunnels Illegal
  Immigration Tunnels
• Brownfields Site Characterization for
  Property/Liability Transfer
• Point of Compliance Site Boundary Monitoring
  (Dedicated System)
• Groundwater/Surface Water Interaction
• Optimize Locations for Water Wells
• Salt Water Intrusion into Drinking Water Wells
• Geotechnical Engineering
• Landfill Leakage
• Others

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Thank You
AdditionalQuestions?
Stop Drilling Blind!
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Dr. Todd Halihan Oklahoma State University School
of Geology 105 Noble Research Center Stillwater,
OK 74078 todd.halihan_at_okstate.edu
Stuart W. McDonald, P.E. Aestus, LLC 2605 Dotsero
Court Loveland, CO 80538 1.888.Geo.Trax or (970)
278-4090 swm_at_aestusllc.com
www.aestusllc.com