A prestigious urban redevelopment in Northern England was located on former industrial site. Soils and groundwater impacted with solvents from historic use as textile factory.

The former underground solvent tank was removed as part of the site clearance works prior to installation of the piled foundations. The in-situ chemical oxidation well array was installed in sympathy with piles and pile caps/beams.

Construction of the multi-storey residential units continued unhindered throughout the treatment process, which was completed on programme (6 months). In order to comply with EA requirements, sign-off was achieved after a further 6 months monitoring of groundwaters.

In-situ oxidation techniques at a former gasworks utilising hydrogen peroxide to remove a complete range of dissolved and adsorbed hydrocarbons varying from PAH to BTEX. Soil conditions at the site varied from sands, silts and gravels to glacial debris with clay lenses, which required closer spaced injection wells. Starting BTEX concentrations of several thousand ppm were reduced to Dutch Intervention Levels over a treatment period of 6 months with a further 6 months of monitoring.

Buried system installed in sympathy with foundation construction works which allowed ongoing treatment throughout the construction programme.

Project nominated for "Innovation Awards 2004".