RRI Company Overview

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RRI Company Overview

• Incorporated August 1992
• Principal Mary-Linda Adams, who has more than
  25 years of experience in the fields of geology,
  geophysics, and environmental consulting.
• Mission Develop and promote the use of
  three-dimensional (3D) subsurface imaging
  technology for environmental engineering, water
  resource, and geotechnical applications.
• Pioneering Technology Performed the first
  high-resolution 3D seismic reflection survey at a
  hazardous waste site.
• Woman-Owned Business

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Services
Groundwater Management Evaluation
Effective Remedial Alternatives
Water Resource Exploration
DNAPL Detection
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Technology

• Seismic Surveys
• 2D/3D Surveys
• Image Stratigraphic/Structural Heterogeneities
• Map Contaminant Migration Pathways Fracture
  Systems

• Photographic Analysis
• Satellite images stereographic pairs of aerial
  photographs
• Fracture trace analysis

• Data Integration
• Detailed site models
• Regional local information

• Geophysics
• Resistivity
• EM / Magnetometry

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Using RRI Technologies

• Site Assessments
• Remedial Investigations (RI)
• Feasibility Studies (FS)
• Remedial Design
• Risk Assessments
• Brownfield Redevelopment
• Water Resource Exploration Evaluation
• Dredging Operations delineation of geology

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Technology Partners
Geophysical Interpretation ExplorTech J. Edward
Blott, Ph.D. (Denver, CO)
Data Processing Excel Geophysical
Services (Denver, CO)
Field Services Bird Seismic Services (Phoenix, AZ)
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Seismic Imaging
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Technology Overview

• Originally developed by the oil exploration
  industry
• Similar to medical imaging technology, seismic
  surveying is the most resolved imaging technique
  that has been developed
• 3D seismic surveys produce data volumes that can
  be viewed in any direction or at any depth

• Information such as faults and fractures, bedding
  planes, the presence of pore fluids, complex
  geologic structure, and detailed stratigraphy can
  be interpreted from 3D seismic data sets.

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Equipment

• Data Acquisition System (seismograph)
• Digitizes geophone signals
• 24-bit accuracy
• Monitors background noise
• In-field quality control

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Equipment

• Seismic Source
• Generates Acoustic Energy
• Elastic Wave Generator (EWG)
• Sledgehammer
• MiniVib

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Equipment

• Geophones
• Detects particle motion
• Attached to earth, pavement, or building floors
• Underwater (hydrophone) wetland (marsh phone)
• Connected to seismograph w/ electrical cables

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Seismic Reflection Surveying

• Acoustic (sound) energy, produced with a seismic
  source, travels through the earth, reflects at
  the boundary between geologic layers, and returns
  to the surface like an echo. The seismic waves
  are measured with sensors called geophones. The
  geophone signals are then digitized and recorded
  by a seismograph.

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2D Surveying

• Single line of geophones
• Data represents thin cross section below line

• Results can be distorted by offline geology

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3D Surveying

• Large grid of geophones
• Data represents a entire volume of subsurface

• Multiple points of observation (range of azimuths
  offsets) increase image accuracy

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Performing a 3D Survey

• 3D seismic reflection surveys are collected using
  a grid of geophones. The recording array is
  incrementally moved across a site to image the
  area of interest.

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Benefits of a 3D Survey

• Image complex geology
• 3D Migration high resolution
• Complete data volume (no gaps)
• Analyze sites along any direction, at any depth

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Certified Technology

• This technology appears to be a useful tool for
  imaging subsurface conditions for the purpose of
  site characterization and for determining the
  most likely locations for DNAPL source zone
  migration and accumulation. As such, this
  technology may prove to be a highly effective
  source exploration tool, particularly in
  fractured bed-rock settings.
• - US Department of Defense, Environmental
  Security Technology Certification Program
  performance report (Oct.1999)

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Work Tasks 3D Seismic Survey

• Background Review
• Site visit
• Literature review local regional geology
• Photographic analysis
• Develop site model
• Mobilize to Site / Testing
• Parameters tests
• Refine survey design
• Land Survey
• Establish 3D grid
• GPS surveying

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Work Tasks 3D Seismic Survey

• Check-shot Survey / Downhole Logs
• Measure seismic velocities
• Model site response
• Aids data processing
• Data used to correlate borehole geology to
  surface seismic data

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Work Tasks 3D Seismic Survey

• Collect 3D Data
• Field QC
• Preliminary processing
• Process 3D Data
• Promax 3D software
• Experts in shallow seismic processing
• 3D refraction statics
• Interpret 3D Data
• Kingdom Suite Software
• 3D Visualization Software
• Analyze site in 3-dimension, data volume along
  any direction at any depth

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Survey Costs

• Project objectives
• Area of interest
• 2D or 3D technology
• Target Depth
• Lateral vertical resolution
• Site access terrain

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Case Study 1Site Characterization
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Overview

• Site Department of Defense (DoD) site in
  California
• Geology Alluvium and lacustrine deposits which
  overlie Tertiary intrusive and extrusive
  volcanic, metamorphic, and sedimentary rocks. The
  area is actively faulted.
• Contaminants Chlorinated solvents perchlorate
  produced by rocket engine testing activities
  impact the groundwater
• Objectives 1) create a bedrock surface map of
  over 12 million sq. ft (1.1 million sq. meters),
  2) characterize the 3D fracture network within
  the bedrock, 3) identify structures that may act
  as groundwater barriers

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Site Diagram

• Survey area approximately 12,340,000 sq feet
  (1,146,000 sq m)

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Stratigraphic Correlation

• Data from check shot surveys borehole logs
  provided information to correlate the site
  stratigraphy to the seismic data

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Imaging Structure

• The structurally deformed rock surface is
  apparent in the seismic cross sections.

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Imaging Structure

• The bedrock overlying unconsolidated sediments
  are cross cut by many fractures and faults, which
  were imaged by the seismic data.

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Imaging Structure

• Bedrock surface horizon (identified during the
  check shot survey) was manually picked on each
  line and crossline throughout the 3D data volume
  in agreement with the known geology at the site.
  A time-structure map of the bedrock horizon was
  then output from the seismic data.
• Velocity data derived from the check-shot surveys
  was used to convert the bedrock horizon times to
  depths.

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Imaging Structure

• 3D visualization software was used to interpret
  the structural geology at the site.
• The seismic data revealed structural highs to the
  west and north, and a low in the center of the
  site.

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Results

• It was concluded that groundwater would flow from
  the structural high in the west towards two small
  subbasins in the center of the former production
  area.
• It appears unlikely that contaminated groundwater
  in the subbasins will flow over the structural
  high to the north. This was an important
  discovery when characterizing the site because of
  the domestic water supply wells located offsite
  to the north.
• The structural features the fracture network
  imaged by the seismic data were used to help
  design remediation efforts that are pending.

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Case Study 2Remedial Design
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Overview

• Site Manufacturing facility in Westlake
  Village, California.
• Geology Overburden, followed by siltstone and
  claystone overlying igneous intrusions with
  numerous thrust faults.
• Contaminants VOCs (TCE). Pump treat system
  installed in 1986, but minimal amounts of VOCs
  were recovered.
• Objectives 1) Image the structure and
  stratigraphy to more accurately characterize the
  site, and 2) Determine the location for more
  successful recovery wells.

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Site Location Photograph
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3D Grid Location
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Data Interpretation Failed Extraction Well

• Seismic Crossline 37 shows a cross section of the
  site underneath a poor extraction well (Well
  EW-2).
• Competent bedrock surface was mapped (blue).
• Many faults cut through the bedrock (black dashed
  lines).
• Faults may act as conduits or barriers for
  groundwater flow and contaminant migration.
• Yield for EW-2 less than 2 gpm (7.5 lpm).
• Seismic indicated well yield is low because of
  location in competent (unfractured) rock
• Recommneded well locations are shown along
  fractured areas interpreted using the seismic
  image (red lines).
• Increased water yield and the potential for
  increasing VOC mass removal might be expected at
  recommended locations because the wells would be
  placed in faulted or fractured areas and
  terminate at structural low point

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Data Interpretation Failed Extraction Well
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Data Interpretation Successful Extraction Well

• Seismic Crossline 70 shows a cross section
  underneath a successful extraction well (Well
  EW-17), near the source area.
• Yield for EW-17 over 15 gpm (57 lpm).
• Well located along an interpreted fracture zone.
  None of the other 47 wells at the site were
  located in fracture zones.
• EW-17 was proven to be in hydraulic
  interconnection to nearby wells via the bedrock
  fractures (pumping tests). EW-17 had over 7 ft
  (2 m) of drawdown while wells closer to the pump
  well had less than 1 ft (0.3 m).

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Data Interpretation Successful Extraction Well
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Data Interpretation Bedrock Surface

• Surface mapping software was used to show the
  configuration of the bedrock.
• It is believed that the configuration of the
  competent bedrock has some control of migration
  of groundwater through the weathered zone to the
  top of the bedrock, and then into fractures.

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Results

• 3 additional wells were recommended for drilling
  based on the seismic data. All 3 wells were
  located within fractured zones in the bedrock.
• Well 1 was located 20 ft (6 m) away from an
  existing 2 gpm (7.5 lpm) well, but it produced
  100 gpm (379 lpm).
• Well 2 produced over 80 gpm (302 lpm), and Well 3
  performed similarly.
• Although all 3 wells produced significantly
  higher yields, they exhibited similar
  characteristic chemistry to existing wells.
• Based on these results the Regional Water Quality
  Control Board (RWQCB) in CA judged that the site
  would best be addressed by natural attenuation.
  The client was allowed to remove the pump and
  treat system and monitor the site.
• Client has realized millions of dollars in
  operation and maintenance cost savings as a
  result of the seismic survey.

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Case Study 3Detecting DNAPL
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Overview

• Site Department of Defense (DoD) site in
  Pennsylvania
• Geology Folded, faulted, and fractured
  Ordovician limestone
• Source A former lagoon (as large as 200 x 50 ft
  60 x 15 m) that was used as a disposal site for
  liquid wastes. TCE and DNAPL is present in the
  groundwater.
• Objectives 1) Image the structure and
  stratigraphy to determine the optimum location
  for recovery wells, and 2) Determine if the
  presence of DNAPL can be detected with the
  seismic method.

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Source Area and Seismic Grid

• A large NE trending fault zone crosses the former
  lagoon source area and the seismic grid

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Interpretation of Structure

• Crossline 44 intersects the source area and the
  fault zone. A black arrow on the data plot
  indicates a fault in the subsurface that was
  easily identified in the seismic data.
• The reflectors in the data indicate an undulating
  and folded stratigraphy that dips to the
  southwest.
• Attenuation of the seismic signal indicates karst
  features at depth, as shown in the red circle

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Detecting DNAPL

• Attribute Analysis A standard seismic section
  is a plot of the particle velocity at the
  geophone versus time. Attribute analysis is
  another method used to examine seismic data by
  isolating a particular attribute of the data.
  Since seismic signals are both functions of time
  and frequency, attribute analysis separates these
  components so that they can be separately
  analyzed.
• Amplitude (envelope) Attribute The exact
  measure (21-bit resolution) of seismic signal
  strength of the seismic data. It can be useful
  for identifying fractured/faulted zones in the
  subsurface, and also areas that contain impacted
  groundwater or DNAPL because these features
  attenuate seismic signals.
• Data Examples Crosslines 41 44 move
  progressively into the source area at the site.
  By using envelope attribute plots the data reveal
  that the area in the subsurface directly below
  the source area produced low amplitude anomalies.
  Confirmatory drilling indicated that these
  anomalies were produced by the presence of DNAPL.

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• Only minor amplitude variations outside of the
  source area

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Fault (migration pathway)

• Large amplitude variations below the source area
  and at depth
• Anomalies at depth represent DNAPL accumulations
  and karst features
• Faulting observed in the standard seismic plot of
  Crossline 44 is also indicated in the attribute
  plot (white arrow)

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Drilling Results
To date 3 wells have been completed, based on the
seismic image. None of the previously installed
wells at the site showed VOC concentrations as
high as two of the four wells that were drilled
during the validation of the seismic
demonstration.

• 2 wells were drilled to shallow depths (lt 100 ft
  30 m) that showed high water yields, one above
  300 gpm (1136 lpm). Both wells were drilled into
  fracture zones as predicted by the seismic
  interpretation. Anomalies seen in the attribute
  analysis are most likely from the fracture zones,
  rather than as a result of attenuation from
  DNAPL, since the chemical analysis in both wells
  was below 1,000 ?g/l.
• A third well was drilled into a fracture zone at
  a trap in the structure at Line 33, with the
  attribute anomaly. As predicted by the seismic
  image, no fluids were encountered while drilling
  until the target depth, about 76 ft (23 m), was
  reached. Analysis of this well showed VOCs as
  high as 3.8 million ?g /l.

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Line 33
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Drilling Results (continued)

• A fourth well was drilled to a depth of 740 ft
  (225 m), but was not completed as a result of
  obstructions in the well. The target depth is
  believed to be deeper, based on the attribute
  anomaly, although it was not possible to place a
  seismic sensor in the hole to verify the one-way
  travel time. An attribute anomaly on Line 39 at
  55 ms or 245 ft (75 m). Analysis of a
  groundwater sample at this depth showed VOC
  concentrations at nearly 50,000 ?g /l. The well
  was then cased off to 280 ft (88 m), before
  drilling continued. At 480 ft (146 m) the VOC
  concentration was nearly 7,000 ?g /l. Prior to
  this work it was believed that contamination
  extended to about 200 ft (61 m). The deep
  attribute anomaly has yet to be drilled (dashed
  on the Line 39 plot).

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Line 39
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