Site transfer between two industrial companies having the same activity

Abstract

Feedback on the application of geostatistics to contaminated sites.

Full text

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 1
Site transfer between two industrial
companies having the same
activity
Florine Garcia1, Christian Cornet2,
Michel H. Garcia1, Jean-Baptiste Mathieu1, Julien Dumont3
1KIDOVA, 2CETIM, 3SERPOL
Technical Day: Geostatistics applied to contaminated soils –Paris –January 23, 2019

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 2
Site transfer between two industrial companies having
same activity: how to manage the environmental
liability?
•An industrial activity since the 80s
•An impact in chromium(VI) in the soils and groundwater,
identified in ~2010
•No access to the production and contamination source areas
because of a sustained industrial activity
•Investigation constraints
•Work constraints
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 3
Assessment of the current soil contamination as part
of the site transfer: an utopia?
•Various expectations from the operator, the owner, the buyer
… Especially a site acquisition subject to the absence of contamination
•Remediation operations are not and will not be completed at
the site transfer time
Required consensus
With a first request for a remediation reliability of 99%, revised down to
90%, and obligation of results…
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 4
As an answer to the expectations: assessment of the
current soil contamination and of the associated
uncertainty
•Rationalizing the survey (number and locations of boreholes,
samples, …) despite access constraints
•And especially providing a geostatistical interpretation to get
the “missing” information
–Critical analysis of the results
–Estimation of the masses of contaminant in place
–Locations of the potential contamination sources
With a shared vocabulary and visuals (masses, contour, cost,
uncertainty, …)
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 5
Presentation of the case study
•Area < 1 ha
•2 production areas, 1 storage area
•Contaminant: Chromium VI (Cr6)
•Difficulty to access contaminated
zone
•38 boreholes (1 m < depth < 6 m)
•Unsaturated zone: 4.5 m thick
Context Methodology Feedback and conclusions
Results
1 m

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 6
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 7
Geostatistical approach
Use of sequential (Gaussian)
simulations
=> generating realistic 3D
contaminant grade images
Stochastic simulations of contaminant grades
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 8
Use of simulation results
200 stochastic simulations of
contaminant grades
Estimation of masses of
contaminants in place
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 9
Use of simulation results
200 stochastic simulations of
contaminant grades
Delineation of likely
contaminated soils based on the
probability that contaminant
grade > critical threshold
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 10
Context
Use of simulation results
200 stochastic simulations of
contaminant grades
Delineation of contamination
sources using soil classification
based on the probability that
vertically cumulated contaminant
mass > critical threshold
Contamination source
Safe soils
Uncertain soils
Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 11
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 14
Simulation of contaminant grades
•200 stochastic simulations
•Equiprobable and realistic 3D images of Cr6 grade
•Local variability from one image to another = local uncertainty
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 15
Masses of contaminant in place
•From the 200 simulations
•Histogram of the masses in place
•Contaminated soil volume that
contains 80% of the mass in
place
Chromium VI
Mean
σ
Min
Q02.5
Q05
Q10
Q20
Q25
Q30
Q40
Q50
Q60
Q70
Q75
Q80
Q90
Q95
Q97.5
Max
Mass in place
(kg) 224
64
108
135
140
156
171
178
187
196
210
228
247
256
270
305
349
390
442
Contaminated
soil volume (m3)
252
70
129
154
161
177
193
202
211
223
237
256
278
289
303
341
388
434
493
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 16
3D visualization of the contamination grades
•Identification & understanding of contaminated soil
extensions
•Taking into account spatial uncertainty
80% chances or more of having
Cr6 grades > 2 ppm 80% chances or more of having
Cr6 grades > 5 ppm
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 17
Calculation of cumulative masses of Cr6
3D realizations of
simulated grades
2D realizations of
vertically cumulated
masses
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 18
Calculation of exceedance probabilities
2D realizations of vertically
cumulated masses
Probability map
for different
thresholds Threshold: 0.1 kg
Threshold: 0.5 kg
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 19
Soil classification derived from probability map
Contamination source locations (P > 0.8)
Safe soils (P< 0.1)
Uncertain soils
•Areas where contamination
sources are likely to be found
•Uncertain zones
–To be further investigated?
–To be included into the
contamination source?
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 20
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 21
Help with comprehension
•The geostatistical interpretation provided everyone with a fast
consensus and an assimilation by the lawyers and the
financiers thanks to
•Rational approach
•2D and 3D visualizations
•Mass in place and contaminated soil volume estimations costs
•Uncertainty calculation
•The database of measurements has progressed during the
investigations
•Using geostatistics for sampling survey design, to conduct the
investigations
… but also after the investigations
Context Methodology Feedback and conclusions
Results

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 22
Context Methodology Feedback and conclusions
Results
Adaptability of the approach
•Taking into account scenarios with virtual boreholes to
complete the data taking into account information on the
sources and the industrial activity
More consistent delineation of the source zones
Lower uncertainties (delineation and masses in place)
•Possible adjustment to the density of data and to the small
size of the site
•Evaluation of the efficiency of the remediation actions already
carried out

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 23
Context Methodology Feedback and conclusions
Results
Decision-making support
•Capacity to answer industrial stakes and to assess
the current soil contamination (delineation and masses in
place)
1) Specifying the responsibilities and enabling the transaction
2) Providing relevant and useful data for later remediation and
dismantling processes

Technical Day: Geostatistics applied to contaminated soils –23/01/2019 24
Context Methodology Feedback and conclusions
Results
Thank you for your attention