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Environmental Geotechnics Case Study

Environmental Geotechnics Case Study. WWII Mustard Gas Factory at Ergethan in the Former East Germany. Site Description. WWII Chemical weapons factory Site in the state of Saxony-Anhalt Approx 3 Km NNW of the town of Strassfurt 5.14 Hectares Former salt mine Present uses Dry Cleaning

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Environmental Geotechnics Case Study

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  1. Environmental Geotechnics Case Study WWII Mustard Gas Factory at Ergethan in the Former East Germany Environmental Geotecnics

  2. Site Description • WWII Chemical weapons factory • Site in the state of Saxony-Anhalt • Approx 3 Km NNW of the town of Strassfurt • 5.14 Hectares • Former salt mine • Present uses • Dry Cleaning • Steel Fabrication Environmental Geotecnics

  3. Introduction • Munitions factories destroyed by Allies at end of war • Many underground tanks missed and have subsequently leaked • Raw materials poorly stored • Bombing destroyed storage and hence caused contamination • Reunification of Germany in 1990 saw the beginning of environmental assessment Environmental Geotecnics

  4. Contamination • Complicated cocktail of contaminants • Mustard Gas • Tear Gas • Arsenic • Extractable Organic Halogens (EOX) • Trichloroethane (dry-cleaning) • Zinc • Present in soil, soil gas & groundwater phases Environmental Geotecnics

  5. Arsenic Main raw material Values up to 53,500 mg/Kg (ie 5%!) Clean up required at >200mg/Kg for As Extractable Organic Halogens (EOX) Values up to 395 g/Kg Extremely contaminated material Significant clean-up required Primary Contaminants Environmental Geotecnics

  6. Proposed Clean-up methods • Inventory of all possibly contaminated sites from archives • Analysis using RAF war-time photographs followed by walk-over surveys • Site survey & sampling (soil, water & gas phases) • Detailed investigation ( including risk analysis) • Remediation & long term monitoring of ground water & aquifers Environmental Geotecnics

  7. 20% of site (10,000m2 to a depth of 6m) requires remediation to remove arsenic & associated contaminants Total excavation of site Carried out under full pressure suit conditions Cost of £10 million Subsequent burial of hazardous waste in secure landfill another £25 million Soil Washing (cost of £15million) Recommended Remediation Work Options Environmental Geotecnics

  8. Soil Washing • Water-based process for scrubbing soils ex-situ to remove contaminants • Contaminants removed in 1 of 2 ways: • Dissolving or suspending soils in the wash solution (sustained by chemical manipulation of pH for a period of time) • Concentrating soils into smaller volume of soil through particle size separation, gravity separation & attrition scrubbing Environmental Geotecnics

  9. Particle Size Separation • Most organic or inorganic contaminants bind chemically or physically to clay or silt particles • Washing separates small Clay & silt particles from larger particles • Effectively reducing volume of contaminated soil Environmental Geotecnics

  10. Gravity Separation Removes high or low specific gravity particles E.g. heavy metal-containing compounds (lead, radium oxide) Attrition scrubbing Removes adherent contaminant films Works best on coarser soils Can increase fines in soils Gravity Separation & Attrition Scrubbing Environmental Geotecnics

  11. Chosen Remediation • Recommended remediation work: • further detailed investigations as to extent of contamination • Complete site encapsulation & long-term monitoring • Chosen remediation • Site fenced off at cost of £3/metre • Simply waiting for money to materialise to clean-up the site Environmental Geotecnics

  12. Thank you Any Questions??? Environmental Geotecnics

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