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International Conference Click to edit Master title style Click to edit Master title style STABILISATION/SOLIDIFICATION TREATMENT AND REMEDIATION Advances in S/S for Waste a member of the a member of the Click to edit Master text styles and

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1 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

International Conference STABILISATION/SOLIDIFICATION TREATMENT AND REMEDIATION Advances in S/S for Waste and Contaminated Land 12-13 April 2005 Cambridge University UK

La Floridienne La Floridienne The First Large Scale The First Large Scale Immobilisation Project in Belgium Immobilisation Project in Belgium

Stany Pensaert – R&D Manager DEC NV

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2 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

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3 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

History of the site La Floridienne History of the site La Floridienne

  • Production facilities of inorganic metal

compounds:

– Ferro- and ferric cyanides → grey waste tip – Lead, lead chloride and lead carbonates → red waste tip

  • In operation between 1930 and 1961
  • Pollution sources:

– Grey waste tip: gypsum-lime nature. – Red waste tip: dust nature. – Ruins of former production plant – Storage and small disposal areas around the production plant.

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4 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Pollution sources on the site

Red waste Grey waste Black waste slurry wall Quaywall combined with slurry wall Former plant area

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5 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Composition of the main sources Composition of the main sources

Red waste Grey waste Immobilisation target (DIN 38414-S4) Concentration mg/kg Leachability mg/l Concentration mg/kg Leachability mg/l pH 4 - 13 3,82 4 12,5 12,7 Arsenic ≤ 1 mg/l 35000-40000

6-8

500-1000 0,01-0,05 Lead ≤ 2 mg/l 2000-10000 0,1-0,5 10000-25000 0,1-10 Zink ≤ 10 mg/l 500-5000 0,1-0,5 500-2000 0,05-0,5 Cyanide total ≤ 1 mg/l 500 0,01-0,1 500-8000

10-300

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6 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Soil contamination

arsenic complex cyanides

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7 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Groundwater contamination

Arsenic –upper aquifer complex cyanides –upper aquifer complex cyanides –deep aquifer

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8 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Headlines of the remediation Headlines of the remediation

  • Vertical and horizontal isolation of soil and

groundwater within the site’s boundaries.

  • Immobilisation of the leachable waste products

and storage within the isolation.

  • Removal of contaminated soil outside the site’s

boundaries and storage within the isolation.

  • Pump-and-treat of the groundwater

contamination outside the site’s boundaries.

  • Permanent lowering of the groundwater within

the site’s boundaries in order to prevent contact with stored waste and soil, and prevent

  • utward flow of contaminated water.
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9 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Immobilisation of the red and grey Immobilisation of the red and grey waste: contractual obligations waste: contractual obligations

  • Contractor is responsible for the design and application
  • f the immobilisation recipes:
  • nly one party involved.
  • Contractor has to guarantee the proposed target levels

for immobilisation:

  • control samples with tender
  • ‘entrance exam’ of 200 m³ of red and grey waste.
  • 50 % of the contract award points on

immobilisation.

  • High risk and liability for the contractor:

extremely high penalties for non-conformance of immobilized waste.

  • Minimal geotechnical stability within 28 days:

17 MPa compressibility modulus

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10 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Contractors risks Contractors risks

  • DEC guaranteed the most stringent levels of

1 mg/l for lixiviation of arsenic and cyanides.

  • From a contractual side the guarantee remains

valid irrespective the chemical quality of the waste that would be encountered in the waste tips.

  • The guaranteed execution period was very short:
  • nly 9 months for the total project, of which only

4 months for the immobilisation:

  • Parallel mixing of red and grey waste.
  • mixing plant capacities of 200 tons an hour.
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11 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Immobilisation of the red waste Immobilisation of the red waste

  • Mobile form of arsenic is arsenate (H2AsO4
  • , HAsO4

2- or

AsO4

3- in function of pH) or arsenite (AsO3 3-).

  • In the presence of iron various interactions with these

arsenic compounds can occur: – adsorption and chemisorption of anionic arsenic compounds on the positively charged Fe(OH)3 – Chemical reaction and crystallisation of iron-arsenic compounds on the iron oxides.

  • At the low pH of the red waste, ferric arsenate will be the

most favourable compound to be formed: Fe3+ + AsO4

3- → FeAsO4 K = 5.3 x 1020

zerovalent iron

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12 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Immobilisation of the grey waste: Immobilisation of the grey waste: which cyanides? which cyanides?

  • Origin: Prussian Blue Fe4(Fe(CN)6)3
  • At the high pH of the grey waste

Prussian Blue is thermodynamically unstable and will dissociate into soluble hexacyanoferrate Fe(CN)6

4- anions in

the pore water and Fe(OH)3.

  • Hardly no free cyanides are present

since Fe(CN)6

4- is a strong complex and

an excess of ferrous ions is present.

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13 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Immobilisation of the grey waste: Immobilisation of the grey waste:

  • ptions investigated.
  • ptions investigated.
  • Lowering the pH of the mixture in order to

stabilize the cyanides as insoluble Prussian Blue.

  • Fixing the cyanides with the addition of cationic

exchange resins. Idea from the water treatment plant as there ionic exchange is used.

  • Transforming the waste matrix to an

impermeable cemented matrix in order to reduce the cyanide mobility within this matrix substantially.

Cement & water repellent additives

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14 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Red waste: mobile mixing plant 30.362 m³ treated 1200 tons of zerovalent iron

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15 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Grey waste: semi-mobile plant 51.537 m³ treated 30000 tons of cement + additives

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16 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

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17 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Results of the immobilisation Results of the immobilisation

Red waste:

  • Arsenic in leachate: 8 mg/l → < 0.1 mg/l
  • Efficiency on arsenic: > 98.5 % increasing

with time.

  • Efficiency on other metals: > 70 %

Grey waste:

  • Cyanide in leachate: 10–300 mg/l → 0.15 mg/l
  • Efficiency on cyanide: > 99 %
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18 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Final capping of the site: 8 ha HDPE 2.5 mm

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19 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Preventive measures (slurry walls, first water treatment) 7.400.000 Remediation TOTAL (€) Environmental consultant 850.000 Contractor (61% for immobilisation) 11.000.000 19.250.000

Some data Some data

  • Start of works: January 2004

End of works: September 2004

  • Costs
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20 a member of the group a member of the group

Contact: Contact:

DEC DEC

Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B B-

  • 2070 Zwijndrecht

2070 Zwijndrecht Belgium Belgium Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53

Info@decnv.com http://www.decnv.com

Thank you for your attention Thank you for your attention Questions ? Questions ?