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Philippe BRANCHU and Laurent EISENLOHR
Philippe BRANCHU and Laurent EISENLOHR
Scientific and Technical network of French ministry for infrastucture
Environmental risk management of the reuse of non-conventional materials
in road construction:application to contaminated
soils Pôle RSTLaboratoireRégionalde l’Ouest Parisien
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 2
PRESENTATION OUTLINE
I. Administrative context
II. Practise evolution 70’- 2007: case studies
III. Non-conventional material management in road construction: Actual practises
IV. Methodology used for characterisation and determining suitability for road reuse
V. Conclusions / Perspectives
ADMINISTRATIVE/LEGISLATIVE CONTEXT
Solid waste management (EU Framework Directive on waste):- Promote valorisation and recycling - Restrict landfill
Sustainable developement
Beneficiation network:<=> economical/geotechnical/environmental criterion
Public works and road construction is a key field for reuse of non-conventional materials
In France administrative / legislative organisation in the 90 ’for:- Municipal solid waste incineration (MSWI)- Pulverised fly ashes- Foundry sands
=> Need for reuse guidelines of solid waste materials in road construction
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 3
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 4
ROAD CONSTRUCTION
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 5
ACTUAL PRACTISES: VALORISATION AND RECYCLING
Secondary raw material (MSWI, Slags,
etc.)
Reduce landfill
Potentially contaminated
soil
Reuse in road construction
sustainable development (i.e. natural resources
conservation)
Potentially non-
conventional materials
Acceptable impacts on the environnment and on human
health in order to
Non-conventional material (MSWI, Slags, …) has demonstrated its
geotechnical suitability as a material for road/embankment construction
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 6
A22 HIGHWAY: 1969-71
Cf. Bulletin de liaison des laboratoires des ponts et chaussées, n°188 (1993)
500’000 tons of Cr ore treatment by-products
were used for embankment
Chromium efflorescence
During the wet seasons, there is a leaching of chromium in these materials and transport to soil and subsurface water bodies
Technically suitable, low costs but contaminated with soluble and toxic Cr=> used in the heart of the road structure with a tightness
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 7
Test road : MSWI (1992), Steel slag (2003) The
environmental impact (analyses of leachate collected beneath the « test road » will be monitored for at least 1 year (1 hydrological cycle)
Cf. Grand Lyon-CETE de Lyon (1995) TSM n° 5 p 427 à 430
(a) construction of the “test road” (steel slag) (b) detail of membranes
(a) (b)
Grand Lyon- CETE de Lyon: Collonges-Au-Mont-d’Or (69)
Test road: monitoring example (steel slag)
50 100 150 200 250 300 350
Cr VI
Cr tot
Cr,
Cr
VI co
nce
ntr
ati
on (
mg/L
)
- 0.1
- 0.3
- 0.5
50 -
150 -
250 -
350 -
50 100 150 200 250 300 350
days
Cum
ula
ted v
olu
me (
L/m
²)
WATER
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 8
days
Data interpretation
- Test roads: how to (un)validate reuse scenarios from monitoring ?
- 90 s MSWI, Fly ashes, Foundry sands reuses based on limited laboratory characterisations => Insufficiant ?
Impact Assessment
=> Eco-compatibility approach(ADEME, 2002) Dépôt ou ouvrage
contenant des déchets
Sol de transfert
Confrontation avec les flux FCA et FCB acceptables par les milieux récepteurs
milieu aquatique, milieu sol
FT
« Transport »
« Source »
« Impact »
FS
Waste eco-compatibility fora given scenario:FT FCA and FT FCB
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 9
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 10
GLOBAL METHODOLY USED FOR CHARACTERISATION AND DETERMINING SUITABILITY FOR ROAD REUSE ….. ENV 12920
FIRST REUSE OF NON-
CONVENTIONAL MATERIAL
Physico-chemical composition
Origin, Variability, etc.
LABORATORY CHARACTERISATION
Batch leaching test, percolation test, lysimeter test, …
FULL-SCALE TEST – ROAD REFERENCE
SCENARII
test road as pilot full-scall, numerical simulation, …
SCENARII IN ROAD CONSTRUCTION
System boundaries, dimensions of road
structure, geotechnical and environmental
approaches, …
Environmentally evaluated from the perspective of the
material itself
bniveau imperm éable
Polluant dissous
substratum
Groundwater flow
aq
uifer
Dissolved pollution
=> Validation / restrictions
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 11
VARIOUS SCENARII: REUSE IN ROAD CONSTRUCTION
- Management of water runoff from road construction
- In order to reduce the release of potential pollution material are confined
Recycled fill
Recycled fill
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 12
Variability assessment, a key feature : MSWI example
Magnetic sep.
ferrous metals
Heavy media sep.
non ferrous metals
Recycling Recycling
Maturation and drying
bedMSWI
Road constructio
n
Leaching testLeaching test
landfill
non OK
OK
Quality Assurance
« test road » FULL-SCALE
OK
Interim storage
Geotechnical & Environmental description: MSWI example
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 13
- Geotechnical and materials testing
- environmental testing (leaching test)
CONCLUSION / PERSPECTIVES
Excavated contaminated soils generally landfilled
Large volumes are concerned
Heterogenous material
A similar methodology should be followed for reuse of contaminated excavated soils (with or without cleanup) in road even if mechanical features are not so good
embankment, landscaping, …
Need for: - specific platform on clean-up sites
- gathering platform for excavated soils
Intersol’2007 6th International Conference-Exhibition on Soils, Sediments and water Slide 14