Interdisciplinary Approach to Reduce Vulnerability and Risks …€¦ · Institut Mines-Télécom...

Institut Mines-Télécom

Interdisciplinary Approach to

Reduce Vulnerability and

Risks related to Polluted

Sites

Case of a metallurgical dump site at

Châteauneuf (Loire, France)

Olivier Faure, Didier Graillot,

Jacques Moutte, Frédéric Paran,

Fernando Pereira, Jordan Ré-BahuaudPhotos O. Faure & J.L. Bouchardon


Context - Issues

How to reduce the risks related to

Polluted Sites ?

Pollutant Transfer

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How to reduce the risks associated with polluted

soils ?

25/11/2016 GSE – UMR 5600 EVS3

Vulnerability = f (S, T, C)

Remove the pollution source

Risque = f (Source, Transfer, Cible/Target)

Degradation and removal of

pollutants decrease the risks

Degradation : many techniques exist, but only for degradable or volatile

pollutants (organics)

alternative technique: dump in waste disposal site


How to reduce the risks associated with

polluted soils ?

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Risque = f (S, T, C)

Risque = f (Source, Transfert, Cible/Target)

By preventing targets from accessing

the site, the risks decrease

Restrict the access to the site

Possible only if the target to protect is a human population, very difficult

(or impossible) in other cases


How to reduce the risks associated with

polluted soils ?

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Risque = f (S, T, C)

Decrease the transfers

Risque = f (Source, Transfer, Cible/Target)

By preventing targets from

accessing the site,

the risks decrease

Setup geomembranes

Build parking lots

Use the waste in road construction

Or …. Phytostabilisation


Phytostabilisation : toward a new technique

of remediation

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A « simple » technique: Implanting a homogeneous and perennial vegetation

cover in order to limit the transfer of contaminants

Phytostabilisation is not a

decontamination technique(the source remains on site)

rather a technique of in situ

confinement, which

fixes the TME’s in the soil


Transfer Routes

potentially affected by PHYTOstabilization

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Transfers « downwards » (lixiviation)

« lateral » Transfers(run-off and aerial / wind erosion)

Transfers « upwards »(bioaccumulation via plants and trophic web)


Aquifers : vulnerability and risks

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Vadose Zone

SW level

(Z river)

Topography (Z soil)

Piézométric level

l

Impermeable substratum

Saturated zoneBottom of the river bed

Puits Well

GW level (Z)GW level (Z)

Vulnerability : vertical

No natural protection

Risk : horizontal

Propagation Velocity

Hydraulic gradient Adapted from

Margat (1988)

and Roux

(2006)

Precipitations

Polluted soil


A Case Study : phystostabilisation

at the Industeel-Loire steel plant

(Arcelor-Mittal)

Site Presentation

Phytostabilisation

Transfer assessment

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Metallurgical dump site, Industeel-Loire

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Is it possible to revegetate quickly and "at lesser expense" a metallurgical

slag dump such as that of Industeel-Loire? Improve the landscape

A double questioning

What is the effect of plants on reducing transfers of contaminants to

receiving media and organisms (groundwater, atmosphere, plants,

animals)? Risk mitigation


Transfers upwards:

toward the vegetation

« accumulator » behaviour

vs

« excluder » behaviour

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Transfers of Metals to Vegetation

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"Global" approach: measurements taken on 5 completely mowed quadrats (50

cm x 50 cm),

Results shown for P5 : optimal conditions of amendment (MIATE) and seeding

(M2)

MIATE : Matières d’Intérêt Agronomique, issues du Traitement des Eaux

mg/kg Al Cr Cu Fe Mn Mo Ni Pb Zn

Measured 145 10.5 4.7 215 45 123 4.5 1 46

Reference

Value *80 0.6 9.1 150 200 0.35 1.7 1 50

* D’après Markert (1992) ou données personnelles

High anomalies for Cr (env. X 20) and Mo (env. X 350)

Slight anomalies for Al (env. X 2), Fe (env. X 1.5), Ni (env. X 2.5)

No anomalies for Cu, Mn, Pb et Zn


Transfers of metals to vegetation

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"Species-wise" approach: measurements on aerial and root parts of dominant

species developing on MIATE

Objective: to identify "biological types" with respect to accumulation

(accumulators vs excluders)

MIATE : composted sewage sludge

Matières d’Intérêt Agronomique, issues du Traitement des Eaux

Institut Mines-Télécom25/11/2016 GSE – UMR 5600 EVS14

For all elements but Molybdenum

most species exhibit "excluder" behavior

For Molybdenum, 6 species out of 10 exhibit an accumulator behavior

The phenotypic "accumulator" trait is more frequent in spontaneous

species than in seeded species


Lateral Transfers:

Estimating the Dust Take Off

Decrease the wind speed at ground

level

Reduce the aerial spread of

contaminated dust

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Effect of vegetation cover on "lateral" transfers:

reduction of wind erosion and dust spreading

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Air entrance

Air exit

(6 fans)

measurement

« Wind Tunnel »

Pitot Probes

(wind speed measurement)

Dust collecting plates


Effect of vegetation cover

on ground wind speed

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0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100

Vit

ess

e d

u v

en

t (m

/s)

Distance au sol (cm)

Sol nu

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100

Vit

ess

e d

u v

en

t (m

/s)


Sol nu

50% de recouvrement

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100

Vit

ess

e d

u v

en

t (m

/s)


Sol nu

50% de recouvrement

95% de recouvrement

Recouvrement : 0% Recouvrement : 50% Recouvrement : 95%

Under the experimental conditions

the presence of a vegetation

cover reduces by 6 the wind

speed at 20 cm above ground



on dust spreading

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0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 20 40 60 80 100

Mas

se d

e p

ou

ssiè

re (

mg)


Sol nu

95% de recouvrement

at 10 cm above ground,

the mass of dust torn from the

substrate is approx. 4.5 times

lower in the presence of plants

at 30 cm above ground,

the mass of dust torn from the

substrate is approx. 3 times lower

in the presence of plants

The presence of plants significantly decreases the mass of dust in the air

between 0 and 50 cm above ground



on aerial transfers of trace elements

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%

Recouv.


10 27 44 61

0% 12 4.8 2.3 1.1

95% 0.4 0.7 0.3 1.2

Réduction

transferts30X 7X 7X =

Mass of Cr (in µg) transported during 20 min by wind at 6 m/s

Recouvrement : 0%

Recouvrement : 95%


Transfer downwards:

estimation of effective infiltration

on plots

Dynamic water balance

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Issues and objectives

Issue: Water is a vector of soil pollution to aquifers (and rivers)

Objective: to estimate the temporal variability and intensity of the effective infiltration flux

• Identify the various components of the water balance affecting infiltration (role of soil reservoir, influence of vegetation cover)

• Model construction (climatic, soil and floristic data)

• Development of simulation scenarii (intensity and temporal distribution of effective infiltration)

• Analysis of simulation results (minimize the amount of effective infiltration)

• Recommendations for better management (risk of pollution)

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Model Description

Conceptual layout and data

Climatic data on site : Daily Rainfall at Châteauneuf (mm)in 2010, 2011, 2012 et 2013

Daily ETP (Potential Evapotranspiration, Penman-Monteith) at Saint-Chamond (mm) computed by Météo France

Pedologic Data for the Plots :Soil thickness(cm)

Grain size : >2mm (%), clay (%), fine silt (%), organic matter (%)

Floristic Data :Vegetation cover (%)

Vegetation type

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Scenarii, Simulation, Results

Current status, forecasts, reference

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Entrées modèle Sorties modèle

Scénarios

Plantes Sol réservoir Sorties

% Ksol

nu Kc

cm % % % % (Terre

fine)

% (Terre

fine) mm %

Recouv. Prof. sol MO Refus (2mm) Terre fine Argile Limons fins Infiltration efficace RU Ieff

0 0,3 0,8 / 0,95 10 3 70 30 3 4 500 1,9 76% Nulbase

Etats actuels

100 0,3 0,8 / 0,95 10 7 70 30 5 5 353 3,2 54% Mbase

100 0,3 0,8 / 0,95 10 11 70 30 5 5 340 4,0 52% M2mo

Prévisions :

amélioration

par

amendement

des parcelles

MIATE

100 0,3 0,8 / 0,95 20 7 70 30 5 5 305 6,5 46% M2s

100 0,3 0,8 / 0,95 20 11 70 30 5 5 287 7,9 44% M2mo2s

100 0,3 0,8 / 0,95 15 7 65 35 4 15 311 6,0 47% M3lim

100 0,3 0,8 / 0,95 15 11 65 35 4 15 295 7,3 45% M2mo3lim

100 0,3 0,8 / 0,95 30 11 65 35 4 15 229 14,5 35% M2mo3lim3s

100 0,3 0,8 / 0,95 50 15 55 45 5 25 139 39,5 21% Sol "naturel" Etats de

Référence 100 0,3 0,8 / 0,95 100 15 30 70 10 25 49 134,9 7% Sol agricole


Conclusions on effective infiltration

Summary and management recommendations• Bare soil : strong infiltration

• Vegetalised amended soil (MIATE) : infiltration decreased30%

• Improved soils : not much different from vegetalised amended soil

• Vegetalised soil of agricultural quality : 70 to 90% reduction in infiltration

Possible Improvements

• Better account of Uncertainties (Zsol, Zracine, Ksol nu, ETP…)

• Refined time analysis (daily time step)

• Taking account of runoff (function of rain intensity)

• Test other pedotransfer functions for scaling the water reserve

• Test several climatic conditions (mediterranean, oceanic, mountain and continental)

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Transfer of metals downwards:

components of the dump site

Various waste: slags, refractories, sandstones, …

Main contaminant :

fusion slags from electric furnaces

Mineralogy:

• Larnite C2S, Wustite (Fe,Mg)O, C4AF, Cr-spinelle

Chemistry:

• 40-50% FeO, 30% CaO

• Chromium 25000 ppm

• Molybdenum 400-800 ppm

• Vanadium 400-800 ppm

• Very low Pb, As, etc

25/11/2016 Modèle de présentation MINES Saint-Étienne25


mineralogy of fusion slag:

Cr-hosting species / mobility


Chromium is abundant, but largely sequestered in spinel

some Chromium is in Ca2(Fe,Al,Cr)O5

-> potentially leached

may become mobile if oxydized to CrO4-2


Lysimeters:

for sampling water leached at 1.5 m depth

3 seed types, 3 amendements :

9 lysimètres 5x10x1.5



Composition of water from lysimeters


4 lysimeters,

1 rain event

Moly

Al

Si

mg/litre

mg/litre


lysimeter output, 2011-2013



Impact of slag dump on the alluvial aquifer

Water from piezometers (2011-2016 on each piezo)


Molybdène

Chromium

underneath

steel plant

underneath

slag dump

pH 6.8 – 7.5 on all piezos

All piezometric levels remain within the alluvial formations

beneath the base of the slag dump


Conclusions

an efficient phytostabilisation (continuous

vegetalized cover) is possible with addition of

composted sludge and metallicolous plant seeds

Aerial tranfer is significantly reduced

Infiltration transfer is limited by enhancing ETR

The slag dump is hyperbasic -> release only

oxyanion-forming metals (Cr, Mo, Al)


Institut Mines-Télécom25/11/2016 Modèle de présentation MINES Saint-Étienne32

Institut Mines-Télécom25/11/2016 Modèle de présentation MINES Saint-Étienne33


Analyse comparative des scénarios

Bilan annuel moyenné

Bilan annuel moyenné de l’infiltration efficace et proportion d’infiltration vis-à-vis des précipitations sur la période 2010-2013 pour tous les scénarios

• Fort abattement de l’Ieff lié à la présence de végétation

• Fort abattement de l’Ieff lié à la présence de sols de « qualité agricole »

25/11/2016 GSE – UMR 5600 EVS34

Etats actuels Prévisions Références



Variabilité temporelle interannuelle

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Bilan par années (2010, 2011, 2012 et 2013) de l’infiltration efficacepour les scénarios les plus représentatifs

• Forte variabilité interannuelle

• Fort effet tampon des sols de « qualité agricole »



Corrélation pluie-infiltration

Corrélation entre intensité de la pluie et intensité

de l'infiltration efficace

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Sol + Végétation

Rôle de tampon

et

d’écrêtement de la pluie



Variabilité temporelle mensuelle

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Bilan mensuel moyenné de l’infiltration efficace sur la période 2010-2013

pour les scénarios les plus représentatifs

• Forte variabilité mensuelle

• Fort effet tampon des sols de « qualité agricole »


Description du modèle

Bilan type réservoir

Dimensionnement RU :

Fonction de pédotransfert :

f°(texture, Zsol, Zracines)[Chiaverini et Gras, 1977]

Pondération ETP

f°(Kc, Ksol nu)- Végétation prairiale (0,8 à 0,95)

- Sol nu (0,3)

- Taux de recouvrement (0 à 100%)

[Allen et al., 1998]

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Outil de modélisation

Vensim, approche systémique

25/11/2016 GSE – UMR 5600 EVS39

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