Remediation Stugsundsudden Söderhamn

Transcription

1 Remediation Stugsundsudden Söderhamn Objectives of stabilisation/solidification Major objective: risk reduction of pollutants concerned, through reduction in mobility/leachability of pollutants into water Chemical Stabilisation: focus at the pollutant, not the matrix solubility or sorption equilibrium specific Solidification: affect the matrix, by result encapsulate the pollutant diffusion control not specific 05/07/

2 Stabilisation: matrices? Soils Any texture: from clayey to gravelly. Coarse soils to be crushed for reaction pollutant additive Beware!! Made ground (Mineral) waste Complex chemistry: focus on several pollutants with complete different physico-chemical behaviour. High salt content might interfere with stabilisation reactions. 05/07/ Stabilisation: contaminants treatable Heavy metals and metalloids Organics: Aliphatics PAHs MAHs (BTEX and phenols) PCBs Cyanides Sulphate 05/07/

3 Implementation Ex-situ mixing plant: Pugmill mixer, planetary mixer, rotary bucket, plough, Advantages: process control, dosing accuracy,high production Disadvantages: excavation necessary 05/07/ Implementation In situ mixing: Dry way: rotary augers, trenching machines, Hydraulic injection: grouting based systems Advantages: no excavation, limited site logistics Disadvantages: difficult proces control, inaccurate dosing, debris sensitive, slow. 05/07/

4 Design of Stabilisation/Solidification STEP 1: Good understanding of reuse criteria and conditions. STEP 2: Thorough characterisation of the soils and its variability, preferably through (re)sampling. STEP 3: Select possible additives or binders. STEP 4: Lab scale mixing trials. STEP 5: validation of treated samples. 05/07/ Performance testing lab scale Leaching tests: appropriate test Stabilisation: often batch tests. Solidification: diffusion tests or batch tests as worst case. Geotechnical tests: UCS (Unconfined Compressive Strength) CBR (Californian Bearing Ratio) Hydraulic permeability Weathering tests: Wet-dry Freeze-thaw 05/07/

5 Case Study 1 The Remediation of La Floridienne at the Kluizendok, Port of Ghent, Belgium Location 05/07/

6 The Situation Chemical company La Floridienne produced metallic salts and ferrous cyanides Site was contaminated with: 75,000 tonnes of cyanide containing waste 60,000 tonnes of arsenic containing waste 05/07/ Remediation concept Immobilisation of all waste piles containing cyanide and arsenic. Storage of the treated material in an engineered cell on site. High stability requirements, due to future destination as container terminal 05/07/

7 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: mg/l 0.15 mg/l Efficiency on cyanide: > 99 % 05/07/ Case Study 2 The Remediation of the Acid Tar Lagoons for Total Belgium in Ertvelde, Port of Ghent, Belgium 7

8 Location 05/07/ Lagoon I: liquid tars Lagoon II: viscous tars Lagoon III: solid and paste tars, spent filter cells 05/07/

9 Materials in the lagoons Acid tar = residue from refining oils by means of oleum (sulphuric acid) = tar-water emulsion + H 2 SO 4 Nature of lagoon material: liquid tars: m³ paste tars: m³ solid tars: m³ filter cells: m³ contaminated soils: m³ 05/07/ Flow Scheme of the Acid Tar Treatment 05/07/

10 The Treatment Plant 05/07/ Situation summer /07/

11 Main Geotechnical Criteria Volume increase Average Obtained Value 25% Objective < 30% CBR Compressibility modulus Hydraulic Permeability Ageing strength loss 14% - 50% MPa to 10-8 m/s < 10% > 11% > 11 MPa < 10-7 m/s < 15% 05/07/ Main Chemical Criteria Initial Value Average Obtained Value Maximum ph , Water soluble part 5% 20% on dry matter 1% 4% on dry matter 10% on dry matter DOC mg/l mg/l 90% reduction 05/07/

12 Case Study 3 The Treatment of Contaminated Soils on a site in East London Location 05/07/

13 05/07/ /07/

14 Remediation of the Site Under the Framework Contract for Demolition and Remediation Works for the a big sports venue in London in 2012, DEC was selected for: Soil Washing Bioremediation Stabilisation / Solidification Thermal Desorption Dredging and Sediment Treatment 05/07/ Remediation of the Site 270 ha Movement of 2.5 million tonnes of contaminated soil, of which 1.5 million tonnes is contaminated. At the end of 2009, DEC treated over 1,000,000 tonnes of contaminated soil through soil washing, bioremediation and stabilisation / solidification 05/07/

15 Soil Stabilisation Plant 05/07/ Stabilisation Objectives Contaminants: Heavy metals Hydrocarbons Sulphate Cyanide Often combined in the soils Reduction of water solubility of the pollutants Reduction of their spreading risk into the groundwater 05/07/

16 Leachability after the use of Organodec Naphthalene Acenaphthylene Acenaphthene Fluorence Phenanthrene Anthracene Fluoranthene Pyrene PAH (sum of EPA 16) % Reduction with 1.5% O- DEC B > 98 > 92 > 97 > 96 > 90 > 89 > 87 > 83 > 97 % Reduction with 3% O- DEC B > 99 > 92 > 98 > 97 > 95 > 92 > 85 > 78 > 98 05/07/ Leachability after the use of Fedec Arsenic (dissolved) Chromium (dissolved) Copper (dissolved) % Reduction with 1% Fedec > 39 > 61 > 42 % Reduction with 0.5% Fedec > 36 > 82 > 34 Zinc (dissolved) /07/

17 Some other ex-situ projects Stabilisation Soil washing residues Tranemo, Sweden, CCA Dublin gasworks, cyanide Terra Cotta, sulphates 05/07/