2009 Stresa SETHI - Politecnico di Torino

Transcript

STRESA – June 19, 2009
Environmental Success In Treatment Objectives - Best Practices In Sustainable Soil, Sediment, and Groundwater
Remediation: An Industry and Regulatory Perspective
Proven Methods for Successfully
Engineered Introduction of Remediation
Reagents in Aquifer Systems
CARSICO
Rajandrea Sethi, Antonio Di Molfetta, Alessandro Ferrero*
DITAG – Politecnico di Torino, Carsico s.r.l.*
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RAJANDREA SETHI, rajandrea.sethi§polito.it Stresa, June 19. 2009
Reagents

Oxidants:

Zerovalent iron (ZVI)
Sodium dithionite

Liquids (miscible, non miscible)

Gases
electron acceptors (i.e. Oxigen);
electron donors (i.e. Hydrogen)

Slurries (suspensions)

Emulsions
Others:

Solids
Biodegradation promoting compounds:

Reductants:

Permanganate;
Fenton;
Ozone;
Sorbent material (i.e. activated carbon, zeolites)
Carbonates
Surfactants - cosolvents
Amendants: mixtures.
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Reactive zones vs
Permeable reactive barriers

Delivery of the reactant close to
the source

Emplacement of the PRB
downstream the source to
intercept the plume

Hot spots (good
characterization)

Multiple/areal sources

Can decrease the remediation
time
Remediation time is controlled
by the rate of dissolution of the
contaminant
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Reactive zones vs
Permeable reactive barriers

Oxidants

Reductants:
Zerovalent iron (ZVI)

Reductants
Micro & Nano ZVI

Others:
Sorbent material (i.e.
activated carbon, zeolites)
Carbonates

Amendants

Amendants
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PRB Construction methods

Excavation Methods:
Unsopported excavation;
Supported excavation:
□ Trench boxes
□ Sheet piling
Continuous Trenching
Biopolymer Trenching
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Biopolymer trenching

A biopolymer (CMC, guar) is used to support the
trench during excavation and then is degraded

Advantages:

eliminates dewatering
provides continuity of the trench
adaptable to a variety of soils and site
less expensive than other methods
Disadvantages:
depth could be a problem
risk of collapsing
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Diaphragm wall excavators
U.S.
Europe
Long stick backhoe excavator
Crane & grab
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Long stick backhoes
BOOM
STICK
Most common
installation
technology for
PRB installation
BUCKET
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Excavation forces
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Excavation Ranges and
Forces
Komatsu PC1250
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LS excavation
+ easy to operate
+ doesn’t require guide wall
- oversized excavators
- precision (high BP usage)
- work across the excavation
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Crane excavator with grab

Developed in early 60’s by an Italian company
(ICOS) that introduced the concept of diaphragm
wall (Puller, 2003)

Most common excavating machine in Europe for
slurry walls

Use in PRB construction (O’Hannesin 2005, PC):
1 pilot scale
-> Borden (Canada)
1 ZVI placement
-> West Vancover (Canada)
1st full scale
-> Torino (Italy)
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Crane excavators
Crane
Grab
(a) Rope suspended
system
+ Depth
- Precision
(b) Kelly mounted
- Depth
+ Precision
(c) Hybrid
+ Depth
+ Precision
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Grabs
(a) Mechanical grab
- Powerfull
(b) Hydraulic Grab
+ Powerfull
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Comparison
Backhoe excavators1
Grab excavators2
Max. power
50 - 485 kW
240 – 400 kW
Base machine weight
7,000 - 110,000 kg
42,000 - 300,000 kg
Lifting capacity
3,500 - 40,000 kg
20,000 - 30,000 kg
Weight of bucket/grab
300 - 3,000 kg
8,000 - 24,000 (kg)
Excavation width
0.4 - 3.0 m
0.5 - 1.2 m
Excavation length
-
2 - 4.2 m
Capacity of bucket/grab
0.2 - 1
m3
1 - 1.2 m3
Bucket/grab digging force (ISO)
50 - 430 kN
300 - 400 kN
Stick crowd force
inversely proportional
to stick length
-
Excavation depths
0 - 30 m
5 - 70 m
Excavation rate
400
m2/day
300 m2/day
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Grab excavator case study
1÷5 Foundry sands
and wastes disposals
CAHs contamination
in
groundwater
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Hydrogeological
characterization
Average parameters
i=0,011
Saturated thickness
b
10 m
Hydraulic conductivity
k
1,8.10-4 m/s
Effective porosity
ne
0,2
Hydraulic gradient
i
0,011
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Contaminant characterization
Direct push
Piezometers
Sampling
points
Soil
samples
Gas
samples
Water
samples
Area 1
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-
95
-
662
>150
Area 1
Area 2
MCL
Max
conc.
µg/l
Max.
conc.
µg/l
µg/l
PCE
0.46
56
1.1
TCE
130
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1.5
cDCE
135
0.3
60
-
0.1
0.5
GW Conc
Area 2
73
130
VC
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Geometry of the barrier

Length:
120 m (17 panels)

Width:
0.6 m (0.5 m of iron)

Height:
11.9-13.8 m

Reactive height:
9.70-11.80 m

Mass of iron:
1700 t

Mass of sand:
360 t
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Excavation technique

Link Belt crawler
crane &
Casagrande
hydraulic grab

thick. = 0.6 m
width = 4 m
capacity= 1030 l

Div. Rodio - TREVI
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Guide wall & end stops
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Biopolymer slurry preparation
Product
Tap water
Guar gum powder
Amount /
batch
3500 l
22.5 kg
Biocide
0.2 kg
Soda Ash
2.5 kg
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Properties of bioslurry

Pseudoplastic yield
fluid

Density: 1020 kg/m3

Dynamic viscosity: 40
cps
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Excavation phase 1
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Excavation phase 2
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Excavation phase 3
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Iron
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Sand
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Mixing truck
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Filling operations
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Bioslurry breakdown
Degradation of the
bioslurry by means of
enzymes recirculation
with air lifting technique
Steve Day, Geo-Solution
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Final configuration of the area
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Light
Piezometer
The PRB now
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Analitycal results
Upstream
PCE
Downstream
U.M.
S27
S28
S35
S36
ug/l
<0.05
<0.05
<0.05
<0.05
TCE
ug/l
25.0
56.0
<0.05
0.4
1,2-DCE
ug/l
15.0
83.0
2.8
1.0
1,1-DCE
ug/l
<0.5
<0.5
<0.05
<0.05
VC
ug/l
<0.05
<0.05
<0.05
<0.05
Total carcinogenic
CAHs
ug/l
40.0
139.0
2.8
1.4
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Technology comparison
Excavation
technology
Max Gate Length
Torino (Italy)
LS case study (US)
Crane with grab bucket
LS backhoe
120 m
68 m
14 m
13 m
52 % volume
89 (140) % volume
18 m2/h
8 days for 120 m
Almost the same
150 $/m2
135 $/m2
Max Depth
Usage of bioslurry
Speed
Excavation costs
@ max depth
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Reagent delivery
(reactive zones)

Injection methods:
Gravity
Fracturing
□ Hydraulic
□ Pneumatic

Jetting
Pressure Pulse Technology
Valved tubings
Direct push
Soil mixing
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Under gravity inside piezometers

Inside 2’’-4’’ piezometers

Small pressure: low viscosity
or high dilution

Low injection rates

Problem:
accumulation
sediment inside the well

Socks can be used
o
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Valved tubings

Technique used in
geotechnical engineering
(permeation grouting)

Valved tubing with selective
injection after isolation with
a double packer

Average pressure (30 bar)

Average radius of influence

Multiple injections
Cattaneo, 2004
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Hydraulic or Pneumatic
Fracturing

Use of very high pressures in order
to generate fractures in the aquifer
filled with the reagent

High injection rates

Non homogeneous permeation and
preferential flow
www.arstechnology.com
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Pressure Pulse Technology
PPT

Derived
from
engineering
oil

Based on the generation
of pressure waves that
determine acceleration of
the interstitial fluid and
transient modifications of
the porous media structure

Not very common
Halliburton
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Soil Mixing

In situ mixing of reagents
(expecially ZVI)

Bentonite and cement can be
added to reduce permeability
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Direct push system

Hydraulically-powered
machines

Environmental sampling
(soil, gas, groundwater)

Grouting and reagents
injection
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Direct push system
Reagents preparation
TRS - Ravenna

Direct injection

Heated

Hydratated and
mixed
www.carsico.it
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Direct push system
Pumps and injection tips

High pressure (69-127
bar)

Average pumping rates

Injection (Top-down or
bottom-up)
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Product rheology

After hydratation:
Few products are newtonian and characterized by a low
viscosity
Most of the products contain organic material,
biopolymers and/or particles: complex rheology usually
shear thinning fluids -> moderate to high pressures
required
Rheology is also influenced by dispersed particles and
colloids which can be subject to filtration inside the
porous media
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AQUAREHAB (EU proj. FP7)
Injection tests
nZVI
µZVI
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Recirculation
Sethi
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Conclusions

Crane & grab excavation is an effective
construction method for PRB emplacement
also for average-low depths

Permeable reactive barriers and reagents
injection are complementary technologies
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Acknowledgements
PRB

PRB Design:
Studio Bortolami e Di Molfetta
Studio Buonomo Veglia
Politecnico di Torino

Contractors:

Technical support:
Edil MaVi, Trevi
I.M.E.S.
E.T.I.
Geo-Solutions

Field Consultancy:

Iron:
Ing. S. Marconetto, Ing. S. Day
Gotthart Maier
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Acknowledgements
NZVI

AQUAREHAB EU project FP7, Coordinator for Politecnico di Torino: Dr. Rajandrea Sethi

Dipartimento del Territorio, dell’Ambiente e delle Geotecnologie, Politecnico di Torino (DITAG-POLITO),
partecipanti: Antonio di Molfetta, Rajandrea Sethi, Tiziana Tosco, Silvia Comba
Dipartimento di Scienza dei materiali e dell’Ingegneria chimica, Politecnico di Torino (DISMIC-POLITO),
partecipanti: Daniele Marchisio
Partners internazionali: Flemish Institute for Technological Research; Katholieke Universiteit Leuven
KULeuven;Geological Survey of Denmark and Greenland; Helmholtz Zentrum München – Deutsches
Forschungszentrum für Gesundheit und Umwelt GmbH; CTM Centre Tecnologic;Technische Universiteit
Delft;Sapion Bodemadvies;ISODETECT Gmbh;University of Stuttgart; Wageningen Universiteit;Ben Gurion
University of the Negev GBU; Masarykova Univerzita;UNESCO-IHE Institute for Water Education;
University of Sheffield; Politecnico di Torino; Hoganas AB; University of Copenhagen; Institut National de
l'Environnement Industriel et des Risques; Environmental Institute - SME
Progetto CIPE C30, Regione Piemonte, Coordinator: Prof. Antonio Di Molfetta

Dipartimento del Territorio, dell’Ambiente e delle Geotecnologie, Politecnico di Torino (DITAG-POLITO),
partecipanti: Antonio di Molfetta, Rajandrea Sethi, Tiziana Tosco, Silvia Comba, Valerio Zolla, Alberto
Tiraferri
Dipartimento di Scienza dei materiali e dell’Ingegneria chimica, Politecnico di Torino (DISMIC-POLITO),
partecipanti: Edoardo Garrone, Barbara Bonelli, Marco Armandi, Francesca Freyria
Dipartimento di Chimica Analitica, Università di Torino (DICHI-UNITO), partecipanti: Claudio Baiocchi,
Claudio Medana, Riccardo Aigotti
Dipartimento di Scienze Mineralogiche e Petrologiche, Università di Torino (DSMP-UNITO): Elena Belluso,
Giovanni Ferraris
INRIM: Marco Coisson, Franco Vinai
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Pubblications

2009 TOSCO T; TIRAFERRI A.; SETHI R. Ionic Strength-Dependent Transport of Microparticles in Saturated Porous Media: Modeling
Mobilization and Immobilization Phenomena under Transient Chemical Conditions. ENVIRONMENTAL SCIENCE AND
TECHNOLOGY

2008 TIRAFERRI A; CHEN K.L; SETHI R.; ELIMELECH M, Reduced sedimentation and aggregation of nanoscale zerovalent iron in
the presence of guar gum, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 2008, ISSN: 0021-9797, DOI:
10.1016/j.jcis.2008.04.064

2008 TIRAFERRI A; SETHI R., Enhanced Transport of Zerovalent Iron Nanoparticles in Saturated Porous Media by Guar Gum,
JOURNAL OF NANOPARTICLE RESEARCH, 2008, ISSN: 1388-0764, DOI: 10.1007/s11051-008-9405-0

2007 SETHI R.; FREYRIA F; COMBA S; DI MOLFETTA A, Ferro nanoscopico per la bonifica di acquiferi contaminati, GEAM.
GEOINGEGNERIA AMBIENTALE E MINERARIA, 2007, ISSN: 1121-9041

2007 FREYRIA F; BONELLI B; SETHI R.; GARRONE E; DI MOLFETTA A, Physico-chemical characterization of colloidal iron
suspensions for groundwater remediation, Marco Petrangeli Papini - Centro Stampa Universita (ITA), 3rd International Symposium on
Permeable Reactive Barriers, Rimini 8-9 nov., 2007, 2007, ISBN: 978-88-87242-98-0

2006 DI MOLFETTA A; SETHI R., Clamshell excavation of a permeable reactive barrier, ENVIRONMENTAL GEOLOGY, 2006, ISSN:
0943-0105, DOI: 10.1007/s00254-006-0215-3

2005 DI MOLFETTA A.; SETHI R., Barriere reattive permeabili, In: Bonifica dei siti contaminati: caratterizzazione e tecnologie di
risanamento., A CURA DI BONOMO LUCA, Mc Graw-Hill (ITA), pp. 562-60

2003 DI MOLFETTA, Ingegneria degli acquiferi. Politeko
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