Cost-effective exploration methods for landfills:

results from the RAWFILL projectFred Nguyen, David Caterina, Itzel Manrique Isunza,

Tom Debouny

1

Agenda of the presentation

• A short introduction to geophysics

• Landfill investigation

• Take home message

2

Applied geophysics: a means to see through

3

Electrical resistivity tomography principles

4

Agenda of the presentation

• A short introduction to geophysics

• Case study from RAWFILL• Site presentation

• Results

• Model

• Take home message

5

RAWFILL 6

Onoz case study

Landfills investigated in RAWFILL

Context: history

7

1963 1971 1976

ashes

2018

(SPW, 2019)

1902-1967: quarry (limestone extraction)

1967-1976: slaked lime deposits followed by ashes

deposits

1982-1987: heterogeneous wastes (inert, tires,

rubber, plastic, car parts, household...)

RAWFILL 8

Site conceptual model

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• Electromagnetic induction (EM)

• Magnetometry (MAG)

• Electrical Resistivity Tomography (ERT) and Induced Polarization (IP)

• Seismic method

– Horizontal to Vertical Noise Spectral Ratio (HVNSR or H/V)

RAWFILL

Mapping

Sounding

Imaging

Selected geophysics

Agenda of the presentation

• A short introduction to geophysics

• Case study from RAWFILL• Site presentation

• Results

• Model

• Take home message

10

RAWFILL 11

EM

Coverage and EMI result

RAWFILL 12

Interpretation: EM

20181976

N

RAWFILL 13

MAG

Coverage and magnetometry result

RAWFILL 14

ERT/IP

ERT lines

Tomography (resistivity and induced polarization)

RAWFILL 15

P1

Limestone bedrock??Fracturedbedrock

LimeLime

??

Waste

Electrical resistivity

Metallic scraps

Chargeability

ERT/IP

Electrical resistivity tomography result

RAWFILL 16

Sampling

P2

Electrical resistivity tomography vs validation

RAWFILL 17

(Debouny, 2019)

Bedrock

Lime

Grey

ashes

H/V measurement Borehole log

𝑓𝑎𝑠ℎ𝑒𝑠

𝑓𝑙𝑖𝑚𝑒

𝑉𝑠𝑙𝑖𝑚𝑒 = 318𝑚

𝑠𝑉𝑠𝑎𝑠ℎ𝑒𝑠 = 271

𝑚

𝑠

Possible to estimate the thickness of ash and lime at other HV stations

Using the resonance frequency to sound

RAWFILL 18

N

From 2D to 3D tomography

Agenda of the presentation

• A short introduction to geophysics

• Case study from RAWFILL• Site presentation

• Results

• Model

• Take home message

19

RAWFILL 20

Translation in a quantified model

Take home messageCase successful here but not a silver bullet (no universal response), it needs to be assisted by complementary data

Landfills Hor./Vert. delimitation is demonstrated > multi-methods very efficient

For composition quantification: requires careful and dedicated processingand laboratory petrophysics

Outlook: Geophysical monitoring to follow leachate injection, membrane leaking , biodegradation/bioleaching

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Thank you

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