1. DEPARTMENT OF CIVIL ENGINEERING ENVIRONMENTAL GEOTECHNOLOGY 2011
Case study: Remediation of contaminated land at Greenwich Peninsula By
Constantinos Tsiolis
Christophoros Christoudias

2. Contents: INTRODUCTION
DESCRIPTION OF CONTAMINATION AT GREENWICH PENINSULA
REMEDIATION STRATEGY AND TECHNIQUES
GREENWICH PENINSULA AFTER REMEDIATION
CONCLUSIONS

3. INTRODUCTION Greenwich Peninsula UK Millennium Exhibition Site
One of the largest gasworks in Europe 1970s
Contamination had occurred principally relating to :
gas production
tar distillation
benzol plant and a chemical works
Figure 0 : Location of the site

4. CONTAMINANTS
Soil : tars, polyaromatic hydrocarbons, volatile organics (from benzol production ,tar production and distillation)
Groundwater : sulphur compounds, ammonia, contaminant from the River Thames aquifer
Ground gas : cyanides and heavy metals (from gas purification)

5. REMEDIATION STRATEGY IN ACTION
The most extensive and complex remediation works were undertaken in the area of both the former tar works and a benzol plant.
Environment Agency was required to evaluate the relevant environmental hazards and risks
Semi-quantitative site-specific risk assessments to develop a remediation strategy:
Statutory Remediation (British Gas)
Redevelopment Remediation (English Partnerships)

6. Statutory Remediation Parts Remediation Technique
1) Statutory Remediation (British Gas)
Statutory Remediation Parts
Description
Remediation Technique
Tar well removal
In-situ
Removal of the contents, structure, and residues from the main tar well
Backfilled excavation based on DTP earthworks specification.
(Fig 2)
Soil Vapour Extraction (SVE )
In situ
The area of volatile organic compounds (VOCs) directly associated with the former benzol plant.
A dual-phase Soil Vapour Extraction (SVE) was designed.
(Fig 3)
Groundwater treatment
Four sources of water were treated.
Treatment plant processes :
pH adjustment=>flocculation=>pressure sand filtration=>air stripping=>biological treatment=>settlement
Materials recycling, reuse and soils washing
Overall, about m3 of natural and engineering materials (e.g. concrete foundations) were recycled for backfilling excavations.
The sequence of operations was generally crushing, screening and washing m3 of soil.

7. Figure 1 : Tar well before removal
Figure 2 : Removing tar
Figure 3 : Soil Vapour Extraction

8. 2) Redevelopment Remediation (English Partnership EP)
Soil contamination was not justified, engineering measures are needed to protect future uses and reduce risks :
Construction of clay capping system (site user protection)
Placement of surfacing capping layer
Capillary break layer (control movements of contaminants)
Clay backfill to service trenches (material protection)
Figure 4 :
Protecting land

9. Greenwich Peninsula today

10. CONCLUSIONS
Millennium Exhibition Site was one of the largest gas works in Europe
Tar works, chemical works and power stations
Contaminants in: soil, groundwater and ground gas.
The principal remediation works were carried out in two phases, statutory and redevelopment.
Crucial risk assessments, experienced contractor team, adopting the most suitable remediation strategy were key aspects to the success.