The decontamination of a disused gas works site

This paper describes work carried out at a site which was to be cleared prior to its use for erection of a large retail superstore together with its adjacent car park. A preliminary site investigation indicated that contamination, especially by tar, was widespread and that numerous underground pipes and tanks were also present. During site clearance approximately 10,000 m³ of contaminated solid material was removed and deposited in two licensed landfill sites 25 km and 40 km from the gas works. Liquid tar was adsorbed onto contaminated solids prior to disposal. A below-ground gas holder was used as a holding tank for contaminated aqueous liquids to enable suspended solids and immiscible organics to separate. After removal of contaminated material the site was covered with clean, crushed and compacted stone having known geotechnical characteristics.