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RAWFILL
Geophysical methods for landfill
characterizationDavid Caterina2, Ben Dashwood1, Itzel Isunza Manrique2, Arnaud Watlet1, Cornelia M. Inauen1
1 British Geological Survey, Nottingham, UK, 2 University of Liege, Urban and Environmental Engineering, Belgium
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“The subsurface site characterization of the geology, geological
structure, groundwater, contamination, and human artifacts beneath the
Earth's surface, based on the lateral and vertical mapping of physical
property variations that are remotely sensed using non-invasive
technologies” (EEGS 2018)
INTRODUCTION
A short introduction to geophysics
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INTRODUCTION
Why geophysics for landfill characterization?
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Accurate information
BUT
Good spatial characterization
can be costly and lead to higher
cross-contamination risks
INTRIDUCTION
Traditional approach:
drilling – sampling - analysis
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Medical analogy
Combine geophysics with traditional techniques
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RAWFILL approach
How?
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Stainless steel electrodesExample: using electrical resistivity
tomography (ERT) & induced polarization (IP)
Principle 1:combine complementary geophysical methods and plan
• Gather and summarize all available information→ Build conceptual model→ Assess knowledge gaps
Geophysical characterization
• Use complementary geophysical methods planned according to the conceptual model→ Interpretation of geophysical results and detection changing properties
Calibration & validation
• Targeted sampling→ Build sampling plan according to geophysical results→ Verify and calibrate geophysical measurements to refine conceptual model
Resource model construction
• Build a resource distribution model based on refined conceptual model
Ad
dit
ion
al
mea
sure
men
ts r
equ
ired
?
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Proposed workflow
Landfill site
Potential knowledge gaps
Type of waste?Volume / Extent of the waste?Cover material?Contamination?
Initial stage
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Proposed workflow
Gather and summarize all available information
• Historical reports (from site owner, local authorities,…)• Aerial photography archives• Previous investigations
• Site visit• Information exchange • Discussing knowns and unknowns of the site
➢ Building conceptual model➢ Assessing knowledge gaps
1 Archives and inventory report
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Proposed workflow
Initial stage After gathering informationand visiting the site
1 Archives and inventory report
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Proposed workflow
Gathering and interpreting a priori information
First conceptual model
1 Archives and inventory report
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Proposed workflow
➢ Filling the knowledge gaps➢ Using non-invasive integrated approach
2 Geophysical characterisation
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Proposed workflow
Mapping techniques
2 Geophysical characterisation
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Proposed workflow
Geophysical imaging (here ERT/IP)
Profiling techniques
2 Geophysical characterisation
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Methods tested within RAWFILL
Method Bulk (geo)physical property
Relevant information for landfill characterisation
Sensitive to
Electrical resistivity tomography (ERT) or DC electrical resistivity