H23G07: Environmental Geotechnology Presentation

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H23G07 Environmental GeotechnologyPresentation

• Mixed Technology Remediation of a Former Chemical
  Works,
• Cadishead, Greater Manchester

By Ka Hang CHAN Ting Ting LIM
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Location
Cadishead Site
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History

• 1900-1965
• Refining crude tar fractioning chemicals
• 1965-2006
• Storage facility for heavy fuel oils
• 2006-current
• Housing plan by Harrow Estates

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Site Detail

• Size of site
• 6.5 hectare
• 120,000m³ contaminated soil
• 6,000m² of groundwater sources
• Potential receptors
• Local residents
• Off-site groundwater receptors in sandstone
  aquifer
• Adjacent sites
• Future users of new homes

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Contaminants
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Remediation Methods

• Alternatives
• Traditional excavate dispose strategy
• Ex-situ biological treatment followed by a
  groundwater treatment

• Multi-technology Remediation
• Ex-situ bioremediation for hydrocarbon
  contaminated soils (90,000m³)
• Ex-situ chemical oxidation (500m³)
• Multi-phase extraction (4000m²)
• Air Sparging (1,000m² 1,000m²)

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Air Sparging

• Principles
• Reducing concentration of volatile organic
  compounds(VOCs)
• Air sparging lances driven into the aquifer using
  direct push technique
• All vapours collected adsorbed by carbon

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How Air Sparging works?
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Air Sparging
Sparging Well
Air Blower
Installation of Sparging Lances
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Air Sparging Pros Cons
Advantages Limitations
Simple implementation Cannot be used if free product exists
Easy equipments Potential for inducing migration of constituents
Cause minimal disturbance Produce a zone of reduced hydraulic conductivity
Short clean-up times
Low cost
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Results

• Over 6.5 tonnes of VOCs recovered
• Project Costs - 6.3m
• 85 - soil treatment
• 15 - groundwater treatments
• Unknown contamination sources
• Odours VOC emissions
• Grant planning permission
• 392 dwellings on the 17 acre site
• Best use of a combination of remediation
  techniques
• Shortlisted in 2008 Brownfield Briefing Awards

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• Any Questions?