Philippe BRANCHU and Laurent EISENLOHR Scientific and Technical network of French ministry for...

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

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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

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ROAD CONSTRUCTION

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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

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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

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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

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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

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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

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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

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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

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- 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

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