BASFORD GAS WORKS REMEDIATION USING SOIL WASHING TECHNOLOGY - PowerPoint PPT Presentation


Title: BASFORD GAS WORKS REMEDIATION USING SOIL WASHING TECHNOLOGY


1
BASFORD GAS WORKSREMEDIATION USINGSOIL
WASHING TECHNOLOGY
2
History of Basford Gas Works
  • 2.5 miles north-east Nottingham city centre
  • Flood plain River Leen
  • Operational 1854 1972
  • Valuable by-products
  • Decommissioned 1972
  • 1995 1997 site investigations
  • Major Contaminants
  • Granular soil soil washing

3
Objectives of Remediation Project
  • Acceptable contamination levels
  • Selective excavation
  • Soil washing
  • Minimise landfill
  • Re-use clean soil
  • Minimise local disruption
  • Minimise environmental impact

4
Project Processes
  • Preliminary investigation
  • Identify need for remediation
  • Test suitability of soil washing
  • Detailed site investigation
  • Full scale remediation
  • Performance assessment

5
Soil Washing - Process
  • Remove debris
  • Mix with water
  • Particle size separation
  • - Contaminants bind to small particles
  • - Small particles bind to larger particles
  • - Washing processes separate small from large
  • Gravity separation
  • - Removes high or low specific gravity particles
    e.g. heavy metal containing compounds
  • Attrition scrubbing
  • - Removes surface contaminant from coarse
    particles
  • Sequential washing

6
Soil Washing - Applicability
  • Originally developed to remove PAHs and PCP
  • Also applies to - Fuels
  • - Pesticides
  • - Various industrial
    chemicals
  • - Metals
  • Removes a wide range of organic and inorganic
    contaminants from coarse grained soils

7
Soil Washing as a solution at Basford Gasworks
  • Efficient technique for contaminant types (mainly
    hydrocarbons) and soil
  • Waste minimisation technique, reduced lorry
    movement offsite (23,000 to 8,000 movements)
  • 14,500 movements saved compared to traditional
    dig and dump
  • Significant recovered quantities of ash clinker
    (steel and breezeblock manufacturing) using soil
    washing

8
Efficiency of Soil Washing
  • 80.5 of input recovered as clean for re-use
  • That unclean usually contained high coarse
    organic content within gravel fraction
  • Most contaminants located in filter-cake - the
    higher the input contaminant concentration the
    more effectively it is washed
  • 15,000t of excavated contaminated soil blended
    with filter-cake to stabilize it

Soil Washing Plant
9
Material Processing
  • 161,650 tonnes of material supplied
  • Processing rate of 370t of clean output/day
  • 125,761t of clean material (sand gravel
    fractions) and 32,240t of filter cake
  • 76 excavation was re-used (compared to 11 for
    traditional methods)
  • Site restored to original ground levels (/-
    0.3m) with the addition of 81,402t clean fill

Clean soil from Washing Plant
10
Alternative Solutions
  • No recommended alternatives
  • Dig and dump would have been cheaper did not
    meet the requirements
  • (Cost of soil washing was 21.11/t)
  • Selective excavation (low cost, low technology)
    was also used in conjunction with soil washing
    (higher cost, higher technology)

11
Summary
  • Only solution to fulfil all objectives
  • Showed that soil washing was effective on a
    variety of contaminants
  • Reduced volumes transported offsite
  • Minimised disruption to local community
  • Significant quantities of recycled materials
  • 30 less energy compared to road haulage
  • 200,000t of contaminated material excavated, this
    represents a substantial saving in landfill void
    space
  • Better results as voluntary project
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BASFORD GAS WORKS REMEDIATION USING SOIL WASHING TECHNOLOGY

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REMEDIATION USING SOIL WASHING ... Process Remove debris Mix with water Particle size separation ... local disruption Minimise environmental impact Project Processes ... – PowerPoint PPT presentation

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Title: BASFORD GAS WORKS REMEDIATION USING SOIL WASHING TECHNOLOGY


1
BASFORD GAS WORKSREMEDIATION USINGSOIL
WASHING TECHNOLOGY
2
History of Basford Gas Works
  • 2.5 miles north-east Nottingham city centre
  • Flood plain River Leen
  • Operational 1854 1972
  • Valuable by-products
  • Decommissioned 1972
  • 1995 1997 site investigations
  • Major Contaminants
  • Granular soil soil washing

3
Objectives of Remediation Project
  • Acceptable contamination levels
  • Selective excavation
  • Soil washing
  • Minimise landfill
  • Re-use clean soil
  • Minimise local disruption
  • Minimise environmental impact

4
Project Processes
  • Preliminary investigation
  • Identify need for remediation
  • Test suitability of soil washing
  • Detailed site investigation
  • Full scale remediation
  • Performance assessment

5
Soil Washing - Process
  • Remove debris
  • Mix with water
  • Particle size separation
  • - Contaminants bind to small particles
  • - Small particles bind to larger particles
  • - Washing processes separate small from large
  • Gravity separation
  • - Removes high or low specific gravity particles
    e.g. heavy metal containing compounds
  • Attrition scrubbing
  • - Removes surface contaminant from coarse
    particles
  • Sequential washing

6
Soil Washing - Applicability
  • Originally developed to remove PAHs and PCP
  • Also applies to - Fuels
  • - Pesticides
  • - Various industrial
    chemicals
  • - Metals
  • Removes a wide range of organic and inorganic
    contaminants from coarse grained soils

7
Soil Washing as a solution at Basford Gasworks
  • Efficient technique for contaminant types (mainly
    hydrocarbons) and soil
  • Waste minimisation technique, reduced lorry
    movement offsite (23,000 to 8,000 movements)
  • 14,500 movements saved compared to traditional
    dig and dump
  • Significant recovered quantities of ash clinker
    (steel and breezeblock manufacturing) using soil
    washing

8
Efficiency of Soil Washing
  • 80.5 of input recovered as clean for re-use
  • That unclean usually contained high coarse
    organic content within gravel fraction
  • Most contaminants located in filter-cake - the
    higher the input contaminant concentration the
    more effectively it is washed
  • 15,000t of excavated contaminated soil blended
    with filter-cake to stabilize it

Soil Washing Plant
9
Material Processing
  • 161,650 tonnes of material supplied
  • Processing rate of 370t of clean output/day
  • 125,761t of clean material (sand gravel
    fractions) and 32,240t of filter cake
  • 76 excavation was re-used (compared to 11 for
    traditional methods)
  • Site restored to original ground levels (/-
    0.3m) with the addition of 81,402t clean fill

Clean soil from Washing Plant
10
Alternative Solutions
  • No recommended alternatives
  • Dig and dump would have been cheaper did not
    meet the requirements
  • (Cost of soil washing was 21.11/t)
  • Selective excavation (low cost, low technology)
    was also used in conjunction with soil washing
    (higher cost, higher technology)

11
Summary
  • Only solution to fulfil all objectives
  • Showed that soil washing was effective on a
    variety of contaminants
  • Reduced volumes transported offsite
  • Minimised disruption to local community
  • Significant quantities of recycled materials
  • 30 less energy compared to road haulage
  • 200,000t of contaminated material excavated, this
    represents a substantial saving in landfill void
    space
  • Better results as voluntary project
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