WSP IS using bioremediation to clean up the site of a former gasworks, petrol station, car workshop and power station in St Peter Port, Guernsey, in the Channel Islands.
The work, for landowner International Energy Group, will enable 8ha of prime site near the seafront to be developed for commercial offices, food retail and housing.
WSP carried out a site investigation and hazardous material survey of buildings, as well as a risk assessment.
Local island authorities were also consulted to agree suitable remediation criteria.
On-site remediation was chosen because Guernsey's landfill sites are not licensed to take contaminated soils, agreements with the UK Government restrict the import of waste and disposal elsewhere in Europe would not have been commercially viable.
WSP designed, managed and implemented the remediation works, working with local engineering firm Miller and Baird which provided plant and machinery.
Soil contaminated with oil hydrocarbons and tar was excavated and treated using bioremediation.
Soil is screened to remove oversized material before nutrients and organic additives are added to optimise treatment.
A phased approach was adopted with areas of the site being released for construction and development as each batch of soil was treated in a six to eight week period.
Some 6,000m 3of soil has been excavated and treated.
Lime stabilisation has also been used to improve the structural properties of soil for use as backfill.