Underground Underground modelingmodeling as a as a tooltool for for impactimpactassessmentassessment ofof productiveproductive processesprocessesassessmentassessment ofof productiveproductive processesprocesses

A li ã d I t d P P d tiA li ã d I t d P P d tiAvaliação do Impacto dos Processos Produtivos e Avaliação do Impacto dos Processos Produtivos e Modelos do Ambiente SubterrâneoModelos do Ambiente Subterrâneo

Jorge MolineroJorge Molinero

São Paulo. 15-18 Setembro de 2009

Outline

Modeling underground hydro-bio-geochemical g g y gprocessesQuantitative evaluation of impacts Can we believeQuantitative evaluation of impacts Can we believe in models?Some examples of underground impact evaluation:• Mining activitiesMining activities• Deep geological repository for Radwaste

CO t• CO2 storage• Civil engineering facilities

Underground HBGQ processes

Can we believe in models?

All models are simplified versions of the reality and underground models are necesarily over-simplified UNCERTAINTY

•CONCEPTUAL UNCERTAINTY Processes

I & B conditions

Time scale

•PARAMETER UNCERTAINTY

HeterogeneityH g n y

Time scale

UpscalingUpscaling …

•MODEL RESULTS (IMPACT ASSESSMENT) must )acknowledge (and quantify if possible) the uncertainty

One complex example…

Iberian pyritic

SotielRiotinto

Tharsis

pyritic belt

Aznalcóllar

SevillaHuelva

Doñana

ESPANYA

DoñanaNational Park

50 km

One complex example…

Aznalcóllar

ESPANYA

50 km

One complex example…

Most sludge retired in 4 months.

But 0.1 to 5 % remainedrepresenting a potentialrepresenting a potential environmental risk.

THE QUESTION:

Sludge

THE PROBLEM: THE QUESTION:

Will the lake be affected?g

Aquifer

Surface water

Unsaturated zone

Aquifer

One complex example…

• PROBLEM TREE

[ ] [ ] [ ] [ ]• PROBABILITY OF FAILURE [ ] [ ] [ ] [ ]ARANPARPANPCAP I−+=

¿Can we evaluate these probabilities?

One complex example…

)(16)(2)()(8)()( 22 HSOFlOHOF S +−+

IF NATURAL ATTENUATION WORKS

P it di l)(16)(2)()(8)()( 24

2222 aqHaqSOaqFelOHaqOsFeS +−+ ++→++

)()()()( 233 aqCaaqHCOaqHsCaCO +−+ +↔+

Mine tailing

Calcite buffers pH

Pyrite dissolves

)()()()( 33 qqqUnsaturated zone

Calcite buffers pH

x>H2AsO4 + H2O ⇔ xO>H + AsO43- + 3 H+

x>HAsO4- + H2O ⇔ xO>H + AsO4

3- + 2 H+ Contaminants adsorbxO>HAsO4

3- ⇔ xO>H + AsO43-

xO>Cu+ + H+ ⇔ xO>H + Cu2+

xO>Zn+ + H+ ⇔ xO>H + Zn2+

Contaminants adsorb on ferrihydrite

AquiferxO>Pb+ + H+ ⇔ xO>H + Pb2+

One complex example…

)(16)(2)()(8)()( 22 HSOFlOHOF S ++ P it di l

IF NATURAL ATTENUATION FAILS9

10)(16)(2)()(8)()( 2

42

222 aqHaqSOaqFelOHaqOsFeS +−+ ++→++Mine tailing

pH drops to acidic values

Pyrite dissolves

456789

pH

Unsaturated zone

Contaminants (such as Cu, Zn, Pb, As, etc.) move freely through the unsaturated zone

01234

Contaminants reach the aquifer0 100 200 300 400

Time (days)

1.0E-02

Aquifer

1 0E-06

1.0E-05

1.0E-04

1.0E-03

aq)]

(mol

/L)

1.0E-09

1.0E-08

1.0E-07

1.0E-06[C

u2+(a

0 100 200 300 400

Time (days)C. Domenech, 2002. Ph.D. Thesis

One complex example…

REMEDIATION ACTION

8

Grain size= 1 cm Porosity=0.4Limestone gravel

Q= 0,1 m/d Q= 1 m/d7

8

pH

Q= 10 m/d5

6p

40,0 0,2 0,4 0,6 0,8 1,0

Barrier thickness (m)( )

YES! Models can help us to determine probabilities by

fquantifying uncertainties PRABolster et al. 2009. Probabilistic risk analysis of groundwater remediation strategies . Water Resources Research, 45,Trinchero et al. 2009. Probabilistic risk analysis of radioactive waste disposal – a case study, Proceedings of American Geophysical Union, Fall Meeting, 2009

A second complex example…

Deep Geological Repository of RadWaste:Canister & Chemical Barrier Engineered Barrier Natural Natural oror Geologic Geologic BarrierBarrier

The question: Will the glaciar water reach the repository?

I Sk di i (S d ) th i f l i ti t b l t d

Will the glaciar water reach the repository? (at a given time T)

In Skandinavia (Sweden) the scenario of glaciation must be evaluated

50Ice Lake

(m) Glaciar

0

Ice LakeHighly diluted water could compromise the stability of

-800-1000 Deep Brine > 1.5 Ma

20 Km

the bentonite

A second complex example…

100 equally probable streamlines crossing the repository

A second complex example…

100 equally probable streamlines crossing the repository

A second complex example…

100 equally probable streamlines crossing the repository

A second complex example…

100 equally probable streamlines crossing the repository

An application example…

> CDF at time T

U d d t f CO

More Examples…

Underground storage of CO2

Main risk related to deep storage f COof CO2

LEAKAGE

Direct emission of Changes in shallowemission of

CO2

Changes in shallow aquifers

U d d t f CO

More Examples…

Underground storage of CO2

CO2 plays an important role in solubility of metals Possiblesolubility of metals. Possible leakage of CO2 could compromise water resources quality Study and modeling of natural analogues

EMPORDÀ

BASIN

1E-03

Testing with natural systems

1E-05

1E-04

measured

with Fe(OH)CO3(aq)

without Fe(OH)CO3(aq)

tion (

mol

/l)

LA SELVA BASIN

1E-08

1E-07

1E-06

Fe co

ncen

trat

0 10 km

1E-09

G d t d T l

More Examples…

Groundwater and Tunnelsa) Potential hazard and control in advancement rate

b) U b t h i l i tb) Urban areas geotechnical impacts

c) Rural areas water resources and environmental impacts

G d t d T l

More Examples…

Barcelona Subway (Línea 9) Groundwater dewatering and ground settlement

Groundwater and Tunnels

A few insights for summary…

Numerical models provide powerful tools for quantitative impact assessment in the subsurface environmentimpact assessment in the subsurface environment

N t i l t i ( b f tNature is always uncertain (subsurface nature even more!). Uncertainty evaluation of model results is a must. P b bili ti h id d th d l tProbabilistic approaches provide a sound methodology to account implicitly for the uncertainties

Some practical examples of quantitative assessment of p p qsubsurface environmental impact have been shown: (1) Minig activities, (2) Waste repositories (3) Civil Engineering g ( ) p ( ) g gworks and (4) CO2 storage…

M itM it b i db i dMuitoMuito obrigadoobrigado……